Beckett vs. Needlewheel skimmers [Archive] - Reef Central Online Community

alwest45

10/02/2006, 01:06 PM

I started a new thread because I didn't want to hijack the Lifereef thread.

QUOTE]<a href=showthread.php?s=&postid=8259072#post8259072 target=_blank>Originally posted</a> by TurboSnail8898
Becketts do have a lot of horsepower, but they are not very efficient when measured against a high quality NW. That horsepower has to come from somewhere and Becketts use massive pumps that are loud, use a lot of energy and produce considerable heat. Space is another consideration. A NW can be very compact and all but the largest can usually be kept under a cabinet. An equivalent Beckett would be between 4' and 6' tall. That's not something that can be kept under the tank. Look into H&S or Deltec skimmers and see why so many are jumping on the bandwagon. I have seen a lot of people go from Becketts to NW, but very few go from NW to Becketts. [/QUOTE]

Hey TurboSnail8898,

I don’t know if you’ve kept up with the latest advances. A modern, well designed Beckett skimmer is none of the things you claim. Just like a needlewheel, it is easy to build a Beckett skimmer without really knowing what you are doing and because they produce so much foam (which is what you are trying to do with a protein skimmer in the first place) they may seem to work ok. However, those companies that have made the investment to engineer all the details right have some very satisfied customers and you don't see them moving away from Beckett skimmers. Here’s specifically where the technology has improved beyond what you may be familiar with:

- the “massive” pump myth. This is really an issue of how the pump companies package their pumps. For the beckett skimmer I’m looking at from Austin Oceans (really a Barr Aquatic design) the Austin Oceans website recommends a Sequence Tarpon rated at 175 watts. The Sequence is a high quality pump with a 3 year warranty and Sequence has great customer service. Basically if your Sequence pump has a problem during the warranty they just take care of it. The Sequence is a low speed pump so it’s quiet – a number of people have these in their living room outside of the stand without a noise issue. And before you start quoting 65 watts (or less) for your needlewheel pump, you have to add in the skimmer feed pump. So that’s 2 pumps for most needlewheel skimmers that both produce noise and use electricity. In many cases it’s a draw when compared with a low speed pressure pump like the Sequence Tarpon. However, this isn’t a big ding against needlewheels. Usually the 2 pumps (or 3 or 4 depending on which model of needlewheel skimmer you have) on a needlewheel are relatively quiet and the electricity usage is close to or only slightly more than the Beckett skimmer pump (which only needs 1 pump no matter how large the skimmer, but it may be a larger pump on larger skimmers). The Sequence pumps are physically larger than 1 of the needlewheel pumps but I don’t think most people are trying to optimize for the physical size of the pump.

- Height. The easy sweet spot for a well designed beckett skimmer seems to be 3-4’. This is enough height to dissipate the energy from the large amounts of foam generated by the beckett. Don’t be fooled by those guys that build 6 foot (or taller) beckett skimmers. It takes a lot more engineering skill to design a really tall skimmer. Check out the DIY section of reef central and you’ll see how some of those guys are having a hard time dealing with the head issues of a 5 or 6 foot skimmer. Some needlewheel skimmer pumps won’t even work well for a 2-3 foot skimmer – they have to use a supplementary air pump to generate sufficient foam (but that works and fortunately air pumps use only a small amount of electricity). There are large, well designed beckett skimmers out there but you have to do your homework to figure out which ones work really well and which ones just put a really long neck on their skimmer to get “marketing inches”.

- Efficiency. This depends on how you measure efficiency. For me, the measure of efficiency is how well and how much the skimmer removes excess organics and other nutrients from my reef tank. From my research, a well designed beckett skimmer is more efficient than any other approach available today. The goal of the skimmer is to produce lots of foam to collect the things you are trying to get out of your tank and then to effectively remove the foam from your skimmer. One of the best measures of how efficient your skimmer is requires that you measure the amount of air going into the skimmer (which is a way to measure the amount of foam produced). If you check again on the DIY board you’ll see the guys there are really focused on this measure. If your needlewheel skimmer uses 15 scfh of air (that’s cubic feet per hour at standard conditions) then everyone thinks you have a pretty decent skimmer. 20 scfh or more is really good for a needlewheel skimmer (yes, I know the about the gutterguard impellor mod and the 30+ scfh numbers – but we’re talking about skimmers you can buy from a real vendor not DIY hotrodding). Many off the shelf needlewheel skimmers do less than 10 scfh. A well designed beckett skimmer can do 45-50 (or more) scfh per beckett (here’s a picture if you are skeptical: http://austinoceans.com/products-skimmers.html#skimmers (look down the page about 12” on the right)). For the beckett skimmer I’m looking at that’s 45 scfh vs. maybe 15 scfh for a really well designed needlewheel skimmer (or 90+ scfh for a dual beckett skimmer!) and that’s using a comparable number of watts. So the beckett skimmer is much more efficient and will remove more “stuff” from the water. They question is whether you need this much efficiency for your reef tank or not. If you just keep softies then probably not. If you keep SPS like I do then the answer is absolutely yes. This is why you are seeing more people look at using beckett skimmers these days. There are now high quality beckett vendors out there (e.g. in another thread in this forum a well respected poster called the GEO and Austin Oceans/Barr products “built like a tank” and the “best build quality”) that don’t have the problems that people saw with old style beckett products but are much more powerful and efficient than any other skimmer out there in terms of what you can buy off the shelf. Some people don’t need this but others need and want it.

Needlewheels are very popular with the masses and there are a number of very decent needlewheels out there (ER, Deltec, H&S, BK, and a few more). I also don't accept Marcs condemnation of Euroreef because of one needlewheel pump that caught fire. The skimmer companies generally don't build the pumps. They are dependent on the pump manufacturer’s quality control. If Sedra (the ER pump supplier) had a big problem with needlewheel pumps catching fire then you would be hearing about it from a lot more people than Marc. For some applications, a needlewheel skimmer I think is probably the right choice. I've done an obsessive amount of research while planning my new reef tank and while I’m leaning towards a beckett skimmer instead of a needlewheel I can see why a needlewheel is the right choice for some people, including:

- a short skimmer to fit under a stand, particularly a shorter stand. It is very difficult for the beckett skimmer companies to contain all the foam generated by a beckett in a short package. So needlewheels are better if you have 2 feet or so to fit your skimmer in since you may not be able to find another well designed skimmer to fit into that space.
- Small tanks with lower skimming requirements. If you tank is smaller than say 50 gallons and you have a small stand then a needlewheel is probably your best choice. At the smaller end of the scale the needlewheel advantages mostly work for you – your skimmer will only have 1 needlewheel pump and the skimmer feed pump can be small (and quiet). If I was starting out with a 30 gallon tank I think a needlewheel is the obvious right choice.
- Non-SPS tanks. If you keep softies and a small number of (non-messy eaters) fish then you don’t need the cutting edge on nutrient removal. A needlewheel is probably a good choice.

As you can probably tell I’ve spent way too much time looking into this issue. For many people a good quality skimmer will work fine for their tank, even a Lifereef (which is apparently easy to maintain and has several very vocal supporters – peace, if it works for you and you’re happy then I have no issue with it). If you care about performance then you have to look deeper. When I look deeper this is what I see. But I welcome any other fact-based data.

Al

Wiskey

10/02/2006, 02:24 PM

Wow, quite a writup, but well done.

I was a fan of NW skimmers, until I got a MRC MR-2, I won't be going back.

Whiskey

McCrary

10/02/2006, 02:31 PM

Hey Al,

I think when compared side by side you may be surprised at some of the skimmate collected by the better NW skimmers. I will link you to some pics, I have the H&S 200-1260 and my friend down the street has the EuroReef RC180. I will show you some of the skimmate that is collected from them. My H&S uses a single Eheim 1260 pump and draws around 14-15 L/min (measured on a Dwyer air meter). The wattage is very low and it is quiet. Some of the better external pumps run on the Becketts may be quiet, but the wattage is still considerable. I almost bought a Barr Aquatics Beckett and would have if he hadn't just sold out to Austin Oceans and wouldn't have been producing them for a few months. But I am very satisfied with the NW skimmers being produced from the better manufacturers.

Here is a link to the most beautiful aquarium I have ever seen and he runs an H&S skimmer. http://www.reefkeeping.com/issues/2006-02/totm/index.php

BreadmanMike

10/02/2006, 02:42 PM

<a href=showthread.php?s=&postid=8263164#post8263164 target=_blank>Originally posted</a> by Wiskey
Wow, quite a writup, but well done.

I was a fan of NW skimmers, until I got a MRC MR-2, I won't be going back.

Whiskey

Went from a Deltec AP851(was hard to let go) to a MRC MR-6R when I upgraded from a 125 to a 180/120 on one system. Love them both and they both work(ed) great. I just don't think you can go wrong with a quality NW or a well built beckett skimmer.

alwest45

10/02/2006, 03:22 PM

<a href=showthread.php?s=&postid=8263219#post8263219 target=_blank>Originally posted</a> by TurboSnail8898

Here is a link to the most beautiful aquarium I have ever seen and he runs an H&S skimmer. http://www.reefkeeping.com/issues/2006-02/totm/index.php

TurboSnail8898,

That is truly a magnificent aquarium. Unfortunately the SAF (which includes space and budget) probably means I won't be getting one like that. But it is a stunning tank and would look really nice in my living room.

Glad to hear you are happy with your H&S. I think it is a good skimmer. I know that Barr was out of production for a few months while they shifted production to Austin Oceans but they have started producing their beckett skimmers again so I have the option to get one. It's really hard to compare skimmate. I think all good skimmers (when properly adjusted) produce lots of nasty looking (and nasty smelling) skimmate. Unless you have the resources to do a chemical analysis of the skimmate you can't really use that as an way to compare the good skimmers. Of course you can use water quality indicators like ORP to try and figure it out but it's hard to run comparison tests that way. That's why I've focused on the airflow as the most effective measurement of efficiency. From that standpoint a well done beckett is the most efficient. But you can also soup up your needdlewheel and get a lot more air through it. Check out the DIY forum for more details.

Your Eheim 1260 (a nice pump by the way) is rated at 65 watts. What pump do you use to feed your skimmer and do you know it's power rating? My friend with a ER uses a Velocity T3 (recommended by his LFS - probably overkill for supplying the skimmer) which is another 140 watts. That's 205watts for the skimmer vs. 175 watts for my Sequence/Reeflo Tarpon beckett pump (if I go that way). Even if you have a lower power supply pump, it's still not a deciding factor (particularly when compared to the 2000 watts I have planned for lighting).

I like the skimmer you got and if I had been purchasing when Barr was switching production I might have gone that way too. But now that they are back I'm trying to figure out which skimmer is the very best - at least as defined for my planned SPS tank. I admit I'm being a little compulsive but this is where I want I can be as compulsive as I want to be.

Al

RichConley

10/02/2006, 03:38 PM

alwest, while I do agree with you that the "needlewheels are teh awesome" is overstated, your numbers arent even close.

You state the beckett uses 165w, and then say NW use slightly more E than becketts because of feed pumps? Thats completely off base.

Your average single beckett pulls 35-40 SCFH. I'm gonna say we can uses that Sequence to drive 2 of them. Thats 70-80 SCFH on 165 watts.

My needlewheel skimmer pulls 40 watts, and pulls 45 scfh when I open it up. It uses a 3w feed pump. How is that even CLOSE? I could throw a second recirc pump on there, have MORE air than the beckett, and around half the energy draw.

alwest45

10/02/2006, 03:40 PM

RichConley

10/02/2006, 03:43 PM

As to the Eheim, its rated 65, but pulls around 40w when running with air.

Your friend running a T3 as a NW feed pump is 1) a waste 2) Negatively impacting his skimmer performance 3) Daft 4) I dont even know..just... what?

I use a minijet to feed my skimmer.

alwest45

10/02/2006, 04:22 PM

<a href=showthread.php?s=&postid=8263472#post8263472 target=_blank>Originally posted</a> by RichConley
alwest, while I do agree with you that the "needlewheels are teh awesome" is overstated, your numbers arent even close.

You state the beckett uses 165w, and then say NW use slightly more E than becketts because of feed pumps? Thats completely off base.

Your average single beckett pulls 35-40 SCFH. I'm gonna say we can uses that Sequence to drive 2 of them. Thats 70-80 SCFH on 165 watts.

My needlewheel skimmer pulls 40 watts, and pulls 45 scfh when I open it up. It uses a 3w feed pump. How is that even CLOSE? I could throw a second recirc pump on there, have MORE air than the beckett, and around half the energy draw.

Rich, I'm talking about unmodded skimmer you buy from a vendor or your LFS, not DIY stuff. I accept your numbers for your setup but I doubt many people get out of the LFS with a 3 watt skimmer feed pump. As I just pointed out my friend left his LFS with a 140w Velocity T3 (and this is from a well regarded and generally good LFS). And good becketts can do 45+ scfh straight out of the box without tweaking. I am comparing what you buy at the LFS or online store and my point was that the difference in power, to me anyhow, is small enough to not be the deciding factor. It doesn't matter if the needlewheel setup is less power or the beckett setup is less power - they are close enough that I'm not going to let it drive my decision. My other point is that when comparing stock, straight from the vendor, skimmers, it's a myth to think that becketts are not as efficient or use huge amounts of power when compared to needlewheel skimmers. By some objective measurements they are more efficient and the power used is close (for standard vendor supplied product).

A BK400 is 68 watts plus feed pump. An H&S A200-2x1260 is 130watts plus feed pump. The ER RC750 is 120w plus feed pump. Even if you are going to use a Mag-Drive 5 (45 watts) as the feed pump that comes to:

BK400 105w
H&S A200-2x1260 175w
ER RC750 165w

Compare this with the Sequence/Reeflo on a good beckett skimmer at 175watts. It just doesn't drive the decision for me. They well designed beckett skimmer will put out much more scfh than the above well regarded needlewheel skimmers. Note that I am using vendor supplied power ratings. It's too hard to go around with a watt measurer and check every pump for actual power usage.

(and note that the only combo here that is substantially under the beckett in power is the BK400, which is $3249 at finsreef.com today - a very nice skimmer but I'm only saving 2 cents per day in electricity vs. the beckett skimmer (70w @ 12cents/kwh) so I would break even in slightly more than 100,000 years...)

Zoom

10/02/2006, 04:30 PM

My skimmer is better than yours Thread.
:rollface: :rollface:

sjm817

10/02/2006, 07:47 PM

Where do you get the idea that NW skimmers need feed pumps?

Also, an Eheim NW 1260 does not use 65W. They use that much when pumping only water. You seem to be inflating the power requirements of NW skimmers.

RichConley

10/02/2006, 07:50 PM

your whole argument seems to be the 140w veloticy t3.

Your friend got ripped off. They should have sold him a maxijet. Plain and simple.

Unmodded, a 1260 pulls 30+ scfh for <40w. Thats way more efficient than a beckett.

McCrary

10/02/2006, 07:54 PM

Energy usage, size, air intake are so variable with each skimmer that it is hard to compare. Add in DIY modifications and there is no easy way to compare. What I want to see is sludge being pulled from the tank. All things considered that is the reason why we put skimmers on the tank. If a Beckett or NW gets the job done then thats what its there for.

RichConley

10/02/2006, 07:58 PM

TUrbo, the point is, if the bubbles are the same size, it doesnt matter what made them. NWs can make more small bubbles for less watts.

McCrary

10/02/2006, 08:06 PM

Rich,

I don't feel that the efficiency of NW's is in doubt. It is very hard to present a legitimate argument stating that Beckett's are more efficient, but an inefficent skimmer that pulls out masive amounts of skimmate would be worth it. I could probably build a skimmer that took in amazing amounts of air and had a very low power consumption and was almost worth less for producing skimmate. Arguments for or against either have to be far more technical and specific or much less.

Carman34L

10/02/2006, 08:18 PM

Where is Spazz when you need him?

alwest45

10/02/2006, 09:41 PM

I know my post was long so it's probably easy to miss some things. And perhaps I left some stuff out to keep it from getting longer. Let me try and clear up some confusion.

1. My skimmer will be external. If I use a needlewheel skimmer I need a feeder pump to get water from the sump to the skimmer. It can gravity flow back to the sump but I need a feeder pump.

2. My friend with the Velocity T3 has a 500 gallon tank. He was shooting for 1.25x turnover in his skimmer, which would mean 625 GPH. He doesn't like Mag-Drive pumps. Given these constraints I don't know that the T3 is a terrible choice (and a Maxi-jet won't cut it). But this doesn't matter to me. In my last post I used a Mag-Drive 5 for the feeder pump calculations. It's 45 watts. It doesn't change the conclusion for what I'm trying to do. I plan to have about 2500 watts of equipment when everything is set up (of course some of it will only run half the time). The 70 watts difference between my current favorite beckett skimmer setup and the low power Bubbleking is only a 3% difference. And the H&S with 2 Eheims is the same amount of power (if you use the skimmer vendors numbers). My analysis says this is close enough for me to disregard it and focus on other factors as more important. My acros don't care how much my electricity bill is and whether I use a beckett or needlewheel skimmer won't make enough difference for even my wife to care.

3. H&S specs their Eheim 1260 skimmer pump at 65w on their website. I know that you DIY guys have measured a lot of this stuff and have different numbers. That doesn't really work for my analysis. I'm sticking with the vendors published numbers. They might be off a little bit but at least I'm being consistent. If you want to complain that H&S is inflating the power requirements of their skimmer I can't do anything about that.

4. My whole point about the electricity requirement was that it's "close enough" so that I'm not using it for a decision. My definition of efficiency isn't how much power the pump uses. My definition is how much air in appropriate sized bubbles gets pumped through the skimmer. More air (or bubbles or foam) means more skimming. That's the efficiency I'm looking at. You can define efficiency however you want. For my analysis, I'm trying to focus on how efficiently the skimmer scrubs the water. More bubbles over a given time frame means better scrubbing.

5. I don't care about DIY mods. I'm only interested in comparing stock, straight out of the box performance. I don't plan to mod my skimmer.

6. I've not seen 30+ scfh for a H&S skimmer with their Eheim 1260 pump. If that's what it does when it comes from H&S that's an impressive number. Still not up to what you could get with a beckett but very interesting. If anyone knows who ran the test on a stock H&S could you point me to the thread or the poster? I know a Sedra powered Euroreef doesn't get even close to that.

I agree that if the bubbles are the same size then it doesn't matter what made them. I want to measure how many bubbles total going through the skimmer, not how many bubbles per watt. And I'm not trying to have a "my skimmer is better than yours" discussion. I'm in the market and hope to buy one of these skimmers sometime soon. My post was how I have evaluated the skimmers out there and which way I'm leaning. I'm looking for any useful fact based feedback or new data that I didn't know (like I could expect that an H&S skimmer with Eheim 1260 pump will do 30+ scfh).

I hope I cleared up some of the confusion.

Al

FMarini

10/02/2006, 09:49 PM

hummmm.. i was hoping to read this thread and come away w/ whats good or better. Instead its kinda sorta a story about trying to justifying your decision to get one skimmer over another.
IMHO-Its pretty much a toss-up as to which skimmer is more efficient- as there are currently no quantitative ways of measuring skimmers.
Beckett skimmers require a high peformance pump- this means it consumes more electricity. I have yet to see a beckett driven efficiently on a low power/low velocity pump. I image that day will come-but not yet. The good news is Beckett skimmer process more water and therefore make multiple passes of the tank water-maybe reducing more organic- maybe not-its untestable. Because of the property of the beckett, it reduces pump flow by 1/2, so if you pumps pumps 1200gph, you'll process 500-600gph. Sounds efficient-right
Aspirating skimmer (NW is not the appropiate term as many of the skimmer described don't use needlewheels they use pegged wheels) are efficient in term of electricity cost. You can drive a great ASP skimmer on a low power pump, primarily because there is NO backpressure on the system, and the impellors do a great job of cavitating and chopping up the incoming air. So in terms of electricity Asp Skimmers are better. Also since there is low water flow in the skimmer body; fatter, wider, and shorter bodies are sufficient to allow foam coalescence. So you can make shorter skimmer. Another point is sound- Beckett skimmer sound like a turbocharger, Asp skimmers are dead slient. Althou I have seen mufflers for becketts-but IMO they work by restricting air volumes-might be reducing the efficiency
As for the only measureable metric on skimmers- amount of air incorporated into the water. You can put a flow meter on the air take of these skimmers and measure the amt of air sucked in/time. Some of the multiple pumps Asp skimmers sucked very large amts of air. A powerful pump on a beckett will do the same.
I know this is an older article, but it is relevant to your discussions (http://www.reefkeeping.com/issues/2002-03/fm/index.php) Since I was around when beckett skimmers started I have a bit of experience w/ them.
Bottomline both skimmers work great (assuming they are good brands), including downdrafts and old skool air driven counter current skimmers-IMO its impossible to state which is more efficient. If it works for you-then its good
frank

RichConley

10/02/2006, 09:51 PM

so basically, you're just going to ignore facts, and go with your preconcieved notions.

This thread is such a morass of misinformation, that I hope no one reads it.

"I agree that if the bubbles are the same size then it doesn't matter what made them. I want to measure how many bubbles total going through the skimmer, not how many bubbles per watt. "

So then you get a skimmer with multiple needlwheel pumps. You're trying to justify wasting electricity, period.

RichConley

10/02/2006, 09:53 PM

H&S A200-2x1260 175w

You're using your own laziness to justify your suppositions.

38w for a running 1260. A mag5 is a joke, run an eheim 1250.

Oh wait, now we're under 100w, and you're wrong.

sjm817

10/02/2006, 10:12 PM

1) Ever hear of gravity feeding? You dont need a feed pump.

3) A 1260 NW does not use 65W. It has nothing to do with DIY. Just facts. Finsreef website is wrong.

5) stock out of the box NW skimmers is what I'm referring to

6). Yes, that is correct. 30+ scfh for ~ 50W Eheim 1260. My ER RS250 is over 33 scfh, 60W total power usage. No feed pump. Stock out of the box.

Zoom

10/02/2006, 10:23 PM

I check my Deltec 851 the single Eheim 1262 use 36 Watts of electricity.
My Deltec 902 has two 1260 Eheims one run at 32 Watts and the other 31 watts.
The return on my 90G tank is a 1260 Eheim that pump use a 62 Watts of electricity but it is a return pump no NW.
On my old Beckett skimmer 830 Aerofoamer i use a iwaki 70 RLT at 354 watts.

alwest45

10/02/2006, 10:58 PM

Rich I don't know you so perhaps I don't understand what you are trying to say. I will say that I'm not interested in getting into personal attacks and if I've said something that upset you I sincerely apologize. Since I don't understand the points you are trying to make in your last 2 posts I'll not respond to those. I am interested in a professional, fact based discussion. Oh, I did get your point that my hypothetical Mag5 wasn't as good a choice as an Eheim. I agree. The 1250 you suggest won't do the flow that was spec'ed in this case but a 1260 will and that's certainly a reasonable choice. I'll pass this on to my friend next time I see him. Thank you for that suggestion.

Frank, thanks for the pointer to the article. Although that was a while ago it was interesting to read and I had not seen it before. Since I am still in the planning stage I am trying to lay out my decisions criteria for selecting a skimmer. It's a lot better to do that now that after I've already bought one. I do think it is possible to do some quantitive analysis on skimmer performance although I agree it is difficult. And I think I've clearly narrowed my list down to good skimmers so it's a matter of picking the best of a good bunch of products. Everyone has their own definition of "best". My definition is different than a lot of the discussion I see in some of these threads. I think the objective measure of how much air goes through a skimmer is a good way to find the skimmer that will perform best for my tank (this assumes that the skimmers all use the air effectively but since I've narrowed it down already to very good skimmers I think that's a safe assumption). The benchmark skimmer and pump combination I've picked to evaluate other skimmers against is a beckett skimmer that uses a 175 watt pressure pump (according to Sequence - it may use less in real life). I am comfortable with that budget. The comparison skimmers are multiple pump NW skimmers (I agree with your point about the name but everyone understands when I say NW skimmer). I would definitely be interested in more data on the measured scfh for H&S, Deltec, Euroreef, and BK skimmers if anyone has it or knows where it is published in a thread. The NW skimmer vendors don't seem as interested in publishing their scfh numbers.

Btw, since you mentioned the noise issue too, I had an opportunity recently to watch a dual beckett skimmer in action. This one had air flow meters on each beckett and they were both running at 45 scfh (a total of 90 scfh). The skimmer was very quiet.

Hey TurboSnail8898, you never said what kind of feed pump you use with your H&S skimmer.

Al

McCrary

10/02/2006, 11:15 PM

Al,

I don't use a feed pump for my H&S. It is run by a single Eheim 1260. The H&S skimmers that are internal aren't recirculating so they don't require pumps to feed them. The external skimmers do require pumps to feed them.

alwest45

10/02/2006, 11:19 PM

<a href=showthread.php?s=&postid=8265125#post8265125 target=_blank>Originally posted</a> by sjm817
1) Ever hear of gravity feeding? You dont need a feed pump.

3) A 1260 NW does not use 65W. It has nothing to do with DIY. Just facts. Finsreef website is wrong.

5) stock out of the box NW skimmers is what I'm referring to

6). Yes, that is correct. 30+ scfh for ~ 50W Eheim 1260. My ER RS250 is over 33 scfh, 60W total power usage. No feed pump. Stock out of the box.

Ok, perhaps I don't get it. I gravity feed back from the skimmer to the sump. I don't see how I can gravity feed to the skimmer, particularly how my space is arranged. Are you taking water straight from the tank overflow before it gets to the sump? I don't think that will work for me and I have to use a feeder pump out of the sump.

Ok, I hear you. Finsreef and H&S websites are wrong on the Eheim power rating. It does make it more difficult to do the analysis if I can't count on the vendors to get it close to right for their own equipment. Do you happen to know if any of the other vendors posted numbers are significantly wrong too or is it just the H&S guys?

Ok, got it.

30+ scfh is a great number for your ER. All the numbers I had were for Sedra pumps and they were significantly less. You don't happen to know what the numbers are for the Gen-X 4100 on the RC750 do you? That was the ER model I was looking at.

Thanks for the feedback.

Al

alwest45

10/02/2006, 11:21 PM

<a href=showthread.php?s=&postid=8265437#post8265437 target=_blank>Originally posted</a> by TurboSnail8898
Al,

I don't use a feed pump for my H&S. It is run by a single Eheim 1260. The H&S skimmers that are internal aren't recirculating so they don't require pumps to feed them. The external skimmers do require pumps to feed them.

Which model of H&S skimmer did you get? This is on a 110 gallon tank?

McCrary

10/02/2006, 11:31 PM

The skimmer is rated for a 300 gallon, its an H&S 200-1260. My tank is over skimmed, especially because I only have two fish in the tank, lol. But SPS don't like DOC's so I try to keep them out of the tank and in my collection cup.

saveafish

10/02/2006, 11:39 PM

becketts are flat out made for big tanks with marketing pushing the desighn for smaller tanks just like needelwheels made for smaller tanks and marketing pushing the desighn for bigger tanks

Hop

10/03/2006, 12:02 AM

<a href=showthread.php?s=&postid=8265458#post8265458 target=_blank>Originally posted</a> by alwest45
Ok, perhaps I don't get it. I gravity feed back from the skimmer to the sump. I don't see how I can gravity feed to the skimmer, particularly how my space is arranged. Are you taking water straight from the tank overflow before it gets to the sump? I don't think that will work for me and I have to use a feeder pump out of the sump.

Al

You gravity feed a NW skimmer off the drain from the tank... In between the tank and the sump on the drain line... No feed pump needed:)

acroporia

10/03/2006, 12:47 PM

Assuming the flamefest from last night has died down, I noticed an interesting post from Euroreef about their new pumps and impellers. This is in the ASM vs. Euroreef thread (http://www.reefcentral.com/forums/showthread.php?s=&threadid=940689&perpage=25&pagenumber=2) and I noticed that Euroreef was trying to make the same point I was, namely that for skimmers that are well designed, the best objective criteria for skimmer efficiency and performance (efficiency defined as how well it skims - in this case efficiency does not have anything to do with electricity usage) is to look at how much air the skimmer is pulling (this assumes again that the skimmer is well designed and uses this air to produce lots of foam and manages the turbulence well so that the foam is properly exited from the skimmer). Let me restate my main point from my posting yesterday and ask for your data based feedback. I think when evaluating a good crop of skimmers and when you are looking to find the one that will be most efficient at removing nutrients, compare the airflow through the skimmer (either scfh or lpm) to determine which skimmer will do the best job. Does anyone know of a reason this would not be true? Keep in mind my assumption that this evaluation will only be done on top performing skimmers that already have a reputation for doing a good to excellent job of skimming.

The specific post from Euroreef announces that their new impellor (announced yesterday) can deliver 1080 lph using the Gen-X 4100 pump (the RC750 has three of these). I think that is about 38 scfh (is this right? Can someone check the math?) so it compares well with the beckett skimmer I was using as my benchmark.

With the new Euroreef numbers I have computed a new set of metrics to compare my skimmer pool. They are:

Skimmer Performance & Skimmer Pump
ER RC750 38 scfh (3 GEN-X 4100 pumps)
Deltec AP902 56 scfh (2 Eheim 1260 pumps)
H&S A200-2s1260 ?? scfh (2 Eheim 1260 pumps)
BK250 (ext) 53 scfh (1? Red Dragon pump)
AO Foaminator MAX 4000 45 scfh (1 Sequence/Reeflo UNO Tarpon)

Does anyone else know the appropriate airflow numbers for the H&S skimmer? Would it be essentially the same as the Deltec numbers? Yesterday I heard 30+ scfh for an Eheim 1260 NW pump. Deltec appears to rate theirs at 28 scfh (assuming I have the conversion right) but it’s possible they are conservative in their rating. If I don’t hear any other input I’ll use 30 scfh for the H&S but it doesn’t seem right to use different numbers for the Deltec and H&S unless someone knows they produce different results.

The NW air flow numbers I had been using were based on some ER Sedra airflow numbers. These are much larger and compare favorably with the beckett numbers (unless I decide to upgrade to a dual beckett skimmer). I am also starting to look much more closely at the H&S skimmer. If it really does 56 (or 60) scfh then maybe it is moving into first place in my evaluation. Based on this data it also appears that both the Deltec and H&S skimmers perform better than the BK although the BK is more expensive (I also backed down from the BK400 – it does 88 scfh – almost the same as the dual beckett skimmer - so it is clearly in a different league than these skimmers)

Any feedback on my methodology or results? I know there are other factors impacting skimmer performance such as geometry and turbulence but for skimmers that already have a proven reputation for being very good skimmers isn’t comparing airflow an effective way to measure the overall performance of the skimmer?

sjm817

10/03/2006, 12:58 PM

The math of 1080 LPH = 38 SCFH seems right to me. That is each SP4 pump. An RC 750 would have 38 x 3 = 114 SCFH

alwest45

10/03/2006, 12:59 PM

Oops. I was using my buddies laptop and the previous post ended up under his name instead of mine. Sorry for the confusion.

Al

alwest45

10/03/2006, 01:06 PM

<a href=showthread.php?s=&postid=8268578#post8268578 target=_blank>Originally posted</a> by sjm817
The math of 1080 LPH = 38 SCFH seems right to me. That is each SP4 pump. An RC 750 would have 38 x 3 = 114 SCFH

Oops again. Thanks for the catch. That puts the RC750 out of the league of the rest of them so I'm substituting the RC500. Here's my new chart.

Skimmer Performance & Skimmer Pump
ER RC500 76 scfh (2 GEN-X 4100 pumps)
Deltec AP902 56 scfh (2 Eheim 1260 pumps)
H&S A200-2s1260 ?? scfh (2 Eheim 1260 pumps)
BK250 (ext) 53 scfh (1? Red Dragon pump)
AO Foaminator MAX 4000 45 scfh (1 Sequence/Reeflo UNO Tarpon)

So now the ER is the new performance leader. Any other corrections or did I get it right this time?

Al

RichConley

10/03/2006, 01:11 PM

Skimmer Performance & Skimmer Pump
ER RC750 38 scfh (3 GEN-X 4100 pumps)
Deltec AP902 56 scfh (2 Eheim 1260 pumps)
H&S A200-2s1260 ?? scfh (2 Eheim 1260 pumps)
BK250 (ext) 53 scfh (1? Red Dragon pump)
AO Foaminator MAX 4000 45 scfh (1 Sequence/Reeflo UNO Tarpon)

Those 4100s pull 38 scfh EACH. Thats over 100 SCFH on the 750.

My problem with Becketts is that theyre teh sledgehammer approach. IE force more air rather than fixing the design issues. Most Becketts done even have tapered transitions: Thats bad design, period.

FWIW, a tinymight driven NW skimmer will pull 100+ scfh at 6' for under 100w.

Roland Jacques

10/03/2006, 01:43 PM

Wow glad you took this out of the Reeflife thread.

I guess we are leaving out in sump models NW, to bad!

For me id build separated sump just so I could run an ATI Bubble Master 250 especially at the price.
40 watts 2200 LPH 77 SCFH!! out of the box ( that still amazes me)

samsfishnchips

10/03/2006, 01:43 PM

manderx

10/03/2006, 01:47 PM

i wouldn't be too quick to say that absolute air throughput is the best way to measure skimmers. i'm using a deltec 851 (after dropping down from a 902) and with both skimmers (both use the same pump), wide open each pump would draw just under 25scfh. however, they skimmed much better when valved down significantly (15-18). this is because with less air being introduced into the pump, it pumped more water, causing more forceful swirling within the body (some people might say smaller bubbles but i don't see it). i can't be sure of this, but it looks like there is more air in the body at any given instant when valved down because the swirling traps more bubbles and keeps them in play longer.

edit: and by swirling i don't mean random chaotic eddies, but deliberate circular motion.

alwest45

10/03/2006, 01:51 PM

Yes, I've fixed the math error. Thanks for pointing it out.

I'm really interested in specifics but I cannot decipher this: Most Becketts done even have tapered transitions. Could you explain in more detail what you meant? If you know if real world examples that's helpful too.

Al

Roland Jacques

10/03/2006, 01:51 PM

<a href=showthread.php?s=&postid=8265541#post8265541 target=_blank>Originally posted</a> by saveafish
becketts are flat out made for big tanks with marketing pushing the desighn for smaller tanks just like needelwheels made for smaller tanks and marketing pushing the desighn for bigger tanks your right their is a lot of truth in that. But technolagy is also pushing the deriction and abilitys of the NW to a larger degree upwards.

to quote my freind Covey talking about the ATI Bubble Master NW skimmer "It's like a energy-effiecent beckett skimmer."

maybe the best of both worlds what do you think?

RichConley

10/03/2006, 02:04 PM

<a href=showthread.php?s=&postid=8268862#post8268862 target=_blank>Originally posted</a> by alwest45
Yes, I've fixed the math error. Thanks for pointing it out.

I'm really interested in specifics but I cannot decipher this: Most Becketts done even have tapered transitions. Could you explain in more detail what you meant? If you know if real world examples that's helpful too.

Al
http://www.barraquatic.com/images/skimmer/sk1220_1.jpg

Thats a Barr. Theyre one of the better beckett skimmers out there, but notice where it goes from body to neck, theres a flange, and not a cone?

At that point, bubbles get stuck, and stick together. Thats why you get burping in becketts, becaues bubbles combine before hitting the neck. Needlewheel skimmers have constantly been tweaked and improved to make them more efficient. Rather than dealing with their design issues, beckett manufacturers add bigger pumps.

Roland Jacques

10/03/2006, 02:05 PM

<a href=showthread.php?s=&postid=8268862#post8268862 target=_blank>Originally posted</a> by alwest45
Yes, I've fixed the math error. Thanks for pointing it out.

I'm really interested in specifics but I cannot decipher this: Most Becketts done even have tapered transitions. Could you explain in more detail what you meant? If you know if real world examples that's helpful too.

Al the transitions of all becketts are step like. the bubles get trap thier and become slightly bigger. they also deposit scum thier as well Harder to clean that it needs to be. Most good Nw use tappered transitions 30-45 degrees bubble flow smothly.

Darn it, i did it again, sorry Rich

RichConley

10/03/2006, 02:06 PM

http://www.aquariumspecialty.com/catalog/images/skimmer_cat_image.jpg

Thats an H&S NW skimmer, notice how theres a cone transition from body to neck?

DocG

10/03/2006, 02:12 PM

I have a dual beckett and a Euro-Reef RC-750 on the same system so I have some insight into this debate (pictures should be in my gallery).

I love both of my skimmers but if I were forced to keep just one it would be the euro-reef.

The beckett can do 1200 lph (42 scfh) per beckett but with that much air it is hard to tune in properly. I run it at 900 lph (32 scfh) and it works great.

The euro-reef pumps run at 840 lph (29 scfh) and I have the taps closed slightly to get better foam. That is with the old impeller.

You can't go wrong with either skimmer.

As for the skimmate - it looks about the same as far as "wetness" goes, the beckett produces 30-50% more skimmate and the Euro-Reef produces much smellier skimmate. I don't know what that means:D

Regarding the 4100's on the RC-750. Because of the size of the skimmer and head pressure these pumps will pull less air then they would on a smaller skimmer. So you are not going to get 114 scfh on the RC-750 with the new impeller. I plan on getting the new impeller so it will be interesting to see what it does do on the RC-750.

JC VT

10/03/2006, 03:53 PM

I'm firmly in the Beckett fan club, even though I couldn't/wouldn't get mine to work (I traded it after a couple of days). When I upgrade to a larger tank, I will be getting one for sure and take the time to dial it in correctly. From what I've researched and read, Beckett's will blow most other skimmers away, especially, as FMarini mentioned, because you can turn your tank over many times. You should always be effective first and efficient second.

My turboflotor, which pulls a decent amount of air, can only handle 100-200gph, and therefore will only turn over my 20L about 7x an hour, since it is gravity fed.

IIRC all the fractionation occurs at the beckett, which means all the water passing through the skimmer/skimmer pump is being fractionated. In a recirc skimmer, the water dumps into a big mixing chamber, where the input may or may not be matched well with the needlewheel pump. I like my turbo because the water input is plumbed directly into the OR2700 intake, so most, if not all, water is passed through the needlewheel before being shot into the reaction chamber.

I also think that too much is being made of tapered necks... most beckett users don't seem to complain that their necks hamper or hinder their ability to skim.

WarrenG

10/03/2006, 04:08 PM

The skimmer I made has a step transition and the step is clear acrylic. I have watched the bubbles under this little "ledge" and they are constantly being stirred into the bubbles near the center (able to go up the neck).

What I notice in the first picture Rich posted is that the neck inside the cup is too short, but the neck in the second picture goes up closer to the cap of the collection cup. I have found this to be helpful because the foam getting pushed up the neck (with air pressure) encounters the cap and gets pushed down the out sides of the neck and into the cup sooner. Or maybe it doesn't matter.

No mention of venturi skimmers here? I tried an Ocean Runner 2700 NW and it was too noisy. I get about the same air, more flow control, and less noise using a mag 3 after a Kent venturi.

hahnmeister

10/03/2006, 04:09 PM

Wow, can believe I missed this thread. Lol. Glad I noticed it after the flaming.

From my own modding/DIYing, I can tell you this. The same pump used as a Beckett/Venturi/Downdraft/Injection pump skimmer pump makes about 1/2 the bubbles that it can make with a needlewheel/threadwheel. As for wattage, according to my Kill-a-watt, the wattage isnt so bad with either though. As you restrict with a Beckett/Mazzei, the wattage goes down since the impeller slows down. With the needlewheel, the air mixing in decreases the amount of work needed, so there is less wattage as well. The Beckett still uses more, but with a eheim 1262, the beckett was running about 50 watts, and the needlewheel was running about 45watts. This is a mag-driven pump however, and other pump like Pan-Worlds and Velocities and ReefFlos might be different. I know their power use increases as you add the restriction of a beckett.

On the same skimmer body (a 4' tall, 8" diameter pipe with bulkheads at various heights for testing), the Dwyer RMC flow meter put the needlewheel at 2x that of the beckett, and a little more for the Mazzei.

But I can see where things get sticky. See, the beckett and Mazzei can pump their output into a skimmer that is easily 6' tall w/o any problems, but as I approached the 4' water level for testing, the needlewheel began to choke and its performance would be surpassed by the beckett and Mazzei (3/4" unit is what I used) if I went to 6' tall.

So then we have the whole 'which is better?' argument from way-back-when... would you rather have a skimmer that is 6' tall, but only 8" in diameter, or a 12" diameter (2x the area of a 8" diameter) skimmer that is only 3' tall (the shorter skimmer with 2x the air throughput as the tall one to maintain the same bubble density to make a fair comparison)?

I would like to dispell one myth out there though... or at least thats how I see it...

Flat riser necks arent that big of a deal unless they are very large. Remember that gravity is not the only thing at play here (er, bouyancy of the bubble depending on how you look at it). There is the flow of the water and air within the skimmer which is flowing upwards. As one bubble hits the 'ceiling' of a flat riser neck on its way up, another will fall rightbehind it, and taking the path of least resistance, the bubble will get pushed towards the inside of the riser rather than the outside (more bubbles build up around the outside then the inside of the riser neck because the area increases as the diameter increases), and eventually to the neck where it can sontinue its path upwards. During this time that the bubble is caught under the flat part, as long as the flow is good enough, and the flat part isnt too large, it has no impact. You will notice that most becketts are tall and narrow in this regard, and if you watch these flat riser areas, there is no buildup or combining of bubbles. The 'updraft' simply carries the bubbles with on their way up. Now dont get me wrong here... lets say you tried to replace the riser cone on a Bubble King with a large flat piece, that skimmer would be a large burping mess.

Roland Jacques

10/03/2006, 06:58 PM

Welcome Hahn Come on in the water's fine, it was hot for a while but it just right now.

While you may not SEE the bubbles connect their in the step I do think it does cause issue that you can see. If you look at any and becketts (I've never seen a Barr in action) just below the final step below the neck cup, you do have waste scum collecting on the sides. If you put a tapperd transition it wont do that.

Has RC allways had spell check?

alwest45

10/03/2006, 11:01 PM

<a href=showthread.php?s=&postid=8271036#post8271036 target=_blank>Originally posted</a> by Roland Jacques

While you may not SEE the bubbles connect their in the step I do think it does cause issue that you can see. If you look at any and becketts (I've never seen a Barr in action) just below the final step below the neck cup, you do have waste scum collecting on the sides. If you put a tapperd transition it wont do that.

The Barr/Austin Oceans skimmer I was leaning towards before the latest ER impeller and numbers looks different than the picture Hahn posted. I can't quite figure out how to post an image here but the picture of the one I was leaning towards is here - the picture is the Austin Oceans Foaminator MAX 5200 - I think Barr called it the SK5220): http://austinoceans.com/products-skimmers.html#Bookmark-SupersizeSkimmer except that the one I was looking at had a single Beckett injector instead of the dual injectors shown in the picture. It's supposed to be easy to add the second injector later if you need additional flow/foam. The one I've seen in operation however is a dual (so we're talking 90 scfh here) and I did not notice any problems with bubbles moving up the neck and out. Nor was there any scum collecting on the sides of the main body. This skimmer was broken in and was running a little on the wet side but it seemed to not have any vices. It was an impressive skimmer in operation. The guy that runs it says he never has burping problems although he did have them with a previous brand of beckett skimmer he owned. Barr implies on his website that he did some engineering specifically to smooth the flow and eliminate burping but he didn't change the flat flange so that doesn't seem to be the problem. Do you know of any research that indicates this might be a problem. I know it seems intuitively like it should work better with a sloping reduction but after having watched the Barr skimmer in operation it did not seem to be impeded at all. I think I’m buying Hahn’s position that it shouldn’t make much difference, at least for beckett skimmers (unless you can point me at some data/research).

Hahn, the Sequence/Reeflo pump curves I've seen show that power usage decreases as head increases. So it seems that the addition of the beckett should reduce the power used rather than increase it.

Roland, can you post a pointer to the ATI Bubblemaster? I'd like to include it in my research list. Other than it uses less electricity, how do you think it compares to the new impeller RC750 (which does 114 scfh using 3 Gen-X 4100s although DocG is sure you won’t see that due to head issues). Since the electrical usage is a small percentage of my overall reef tank equipment, I’m more interested in how much water scrubbing I can get out of the skimmer so I am looking for the maximum number of very small, properly behaved bubbles I can get.

DocG, please post your measured numbers for your RC750 when you get the new impeller. According to ER you can order them now. Any chance of that happening soon? Also, which beckett skimmer do you have? The guy I know with the dual beckett Barr was able to run his wide open from almost the first day without problem. It came with dual airflow meters so he can see how many scfh he is getting – when it drops below 45 scfh per beckett he knows it’s time to clean the beckett, which he says he does every month. Is this the same as your experience?

WarrenG, I looked at venturi skimmers and came to the conclusion that beckett skimmers (which are in some ways an evolution of the plain venturi designs) produced more airflow/foam and would outperform the plain vanilla venture or Mazzei venturi skimmers. Do you have any references to venturi skimmer products (not DIY stuff) that measure and post their airflow numbers? The few that I've seen were way off the numbers we are talking about here – but they were engineered a good while ago so may not be the state of the art. Also, the neck height I think depends on the airflow. On the 90 scfh dual beckett Barr skimmer I've seen, the foam is forced up and over pretty forcefully so it seems like the neck ends in a good place for that level of airflow. Perhaps in lower airflow skimmers you need the neck to extend up further?

manderx, that's a tough thing to measure. Do you have any more insight into how the performance is related to airflow? Are you also saying that you think some/most Deltec skimmers turn down the airflow to get more efficient/better skimming? Do you think that implies their design is a little deficient when it comes to supporting higher airflow? Don't you want your skimmer to be engineered to produce more small bubbles when you turn the air up (particularly when you supply both the skimmer and pump like Deltec does - I'm not bashing Deltec, just curious).

Al

hahnmeister

10/03/2006, 11:45 PM

"Hahn, the Sequence/Reeflo pump curves I've seen show that power usage decreases as head increases. So it seems that the addition of the beckett should reduce the power used rather than increase it." -alwest45

http://www.marinedepot.com/IMD/pump_mdm_sequence_reeflo_dartcurve.jpg

As the head increases from 0, the wattage increases from 140ish to 160ish, before going down again. For many, this 'sweet spot' lands them at the 160watt mark. Not that I would suggest a Dart to power a beckett, but Cuda's and Hammerheads are the same, as are many other shaft driven pumps.

As for your conversation with WarrenG, one would assume that a beckett would draw more air because it has more ports, etc... but this is not always the case. If you look at how the conservation of energy equasions work, it pretty much says that the faster a liquid accelerates, the more it's pressure drops. So the smaller the pipe diameter, the faster the water must travel. And while the Mazzei might only have one port for air/water to pass through, and less area at that, rather than a large circle/ball to pass around with multiple air inlets, it is able to accelerate the water more, creating more of a vacuum. The Beckett could be assumed to draw in more air if it was considered that the airflow was restricted... but air has such a low viscosity that this just isnt the case. Keep in mind what Becketts were designed for... not skimmers, but as a low pressure foaming bubble nozzle for fountain pumps.... often run with lower pressure pumps. They were never designed to outperform a Mazzei/Venturi of good design.

Zephrant

10/03/2006, 11:57 PM

<a href=showthread.php?s=&postid=8272513#post8272513 target=_blank>Originally posted</a> by hahnmeister
They were never designed to outperform a Mazzei/Venturi of good design.

Ahh, but they do. I guarantee that the Beckett manufacturers would use Mazzeis if they worked better at high flow rates. There is no reason not to.

Your logic is correct, but at the flow rates and pressures that we see in typical aquarium pumps, the Beckett just runs circles around a Mazzei.

Mazzeis were designed for injecting relatively low volumes of Oxygen or other gasses in to a water stream in industrial situations. They were not designed for skimmers either.

Zephrant

10/04/2006, 12:07 AM

It is always tough to measure skimmer performance- I'd would like to mention that raw air flow is not very meaningful without considering the water flow too. While there is a maximum amount of air that can used and still get "foam" (and not just a top-off-of-the-blender effect), some designs can run just fine on far less than that maximum number. I'd suggest that a SCFH/GPM measurement might be useful, but that does ignore the system water volume which I feel has a far greater impact as the well-being of the inhabitants.

The three skimmer traits that have the most impact on how each skimmer performs are:
- Air flow (and associated bubble size)
- Water flow
- Water volume

And to a lesser extent, water path. These all combine in to some useful numbers:
Dwell time- skimmer water volume, divided by input water in gallons per second gives the number of seconds that the average water particle will be "in play" in the skimmer. This is a very rough average, as it depends greatly on the skimmer design. Picture a long tall counter-current tube, vs. a short square box. Both could have the same dwell number, but very different performance. But for similar physical designs of skimmers, this is a good measurement.
Contact length- This is somewhat overlooked, but I feel it is important. This is the minimum distance that every particle of water must travel before exiting the skimmer. For some designs, this could be as little as 6 inches. For others, it is over a hundred. For a full system picture the minimum, average and maximum numbers should be known.

As mentioned above, power draw is a valid concern, but as I've not seen the math posted yet, how about this:
165 watts is 1.375 Amps at 120VAC. Running 24/7 that is 27.7 K watt hours per week, or about 1441 KWH per year. I have dirt cheap power (less than $0.05 a KWH), so it would cost me $1.39 a week or $72 per year to run a 165W skimmer.

Mentioned above is the question "Why do Beckett's not have tapered necks?" As Hahn mentioned, a well designed, high-air flow skimmer does not benefit noticeably from a tapered neck in the 6-8" diameter models that we typically see in home aquaria. For my own designs, the negligible performance difference does not warrant the associated costs to use them.

There are always trade-offs in any design. I've noticed a tendency to assume the manufacturers don't know what they are doing (I do this myself for non reef-related things), but in reality, the big name manufacturers have all spent years trying different things out and selecting the best ideas to build. Look at Frank's article above- how many skimmer neck designs did PM test to find the best one? I've got a whole room full of test mules for various concepts. Some worked better, some didn't. Some worked well but were not worth the costs, as there was an easier way that became obvious during testing.

That's not to say there are not a few "features" out there that are purely marketing speak- try as we might, those sales guys do get in the way of us engineers at times. That's why they get the big bucks though. :)

Rough list in my suggested order of priority of things that impacts a skimmer's performance:
Tank volume
Tank inhabitants, including algae and any scrubbers (waste generation level, and type of waste)
Feeding regime
Skimmer's water flow / Air flow / Water volume
Skimmer intake/exit (Recirculating or flow-though)

In this thread, we are focusing only on the skimmer air flow, a subset of item 4 on my list, which just is not enough data in and of itself, to determine how a skimmer will perform in any situation.

These discussions are great- I really enjoy seeing the data too- Please keep it up. ;)

hahnmeister

10/04/2006, 12:30 AM

<a href=showthread.php?s=&postid=8272557#post8272557 target=_blank>Originally posted</a> by Zephrant
Ahh, but they do. I guarantee that the Beckett manufacturers would use Mazzeis if they worked better at high flow rates. There is no reason not to.

Your logic is correct, but at the flow rates and pressures that we see in typical aquarium pumps, the Beckett just runs circles around a Mazzei.

Mazzeis were designed for injecting relatively low volumes of Oxygen or other gasses in to a water stream in industrial situations. They were not designed for skimmers either.

You dont even make your own stuff anymore, so you cant talk...lol:D At higher rates, yes, the beckett does perform better because its more restrictive and so it accelerates the water faster.

I would imagine a larger Mazzei would run circles around a Beckett just the same. Both are excellent mixers, FWIW... you just have to know how to use them properly.

Roland Jacques

10/04/2006, 06:44 AM

Wow these thread keeps getting better.

I would add Foam stability to these 3 and probably put it at the top. But for some this is already a given.

"The three skimmer traits that have the most impact on how each skimmer performs are:
- Air flow (and associated bubble size)
- Water flow
- Water volume"

I agree that focusing on air volume only is not enough data to be completely useful, but it is a go starting point or ending point.

Bar mentioned the water flow but I don’t see those numbers in the web site. I no each pump will perform different but maybe they can give a example numbers for the becketts. (Iwaki 70 ;15 psi pump; pulling 45 scfh of air also allows XXX gallons of water or something like that)

Like I said alwest, ive not ever seen a Barr in action so it might not have that waste scum collecting issue. Also, I have not seen many many skimmers, so when I say all Becketts I should say that I’ve seen. Also cleaning inside the body of a skimmer is a personal issue for me because I spent many years cleaning tanks for a living and those 5 extra minutes here and their clean something that should no be dirty just gets me.

The watts thing is very interesting, I don’t think ive given that enough confederation (spell check, move to the south and this is what your spell check starts doing. lol ) in the past. My KWH is $0.10 so that Barr skimmer would cost me $142 dollars a year @162 watts. And my Mazzei 7’ skimmer cost me $340 a year, with the 340watts Iwaki 100rlt running it. When I switch it over to the NW & Air pump 100 watts total it cost $100 year. I for one am going to be a lot more power conscience (spell check please)in the future.

I tested the “New?” ER Gen-x 6000 I really like the pump/impeller combo run it detec style and its pretty quit to. Here the results I got on my skimmer at different head pressure. (note I may be reading my flow meter on the low side, but I compare impellers with the same flow meter and read it the same way. I think compared to how most people read their meter you could add 3 SCFH to those numbers)

Water head 6", - SCFH 41, - Watts 47 .
Water head 12", - SCFH 33, - Watts 50 .
Water head 18", - SCFH 28 - Watts 53 .
Water head 24", - SCFH 25, - Watts 59 .
Water head 30", - SCFH 23, - Watts 62 .
Water head 36", - SCFH 19, - Watts 65 .
Water head 42", - SCFH 18, - Watts 66 .
Water head 48", - SCFH 17, - Watts 68 .
Water head 54", - SCFH 15, - Watts 69 .

From what I can tell so far the BM type impeller beats it hands down. The the thing is different pumps are more faviortable to one impeller type over another and at different pressures.

As far as the Bubble Master I was wrong about the watts being 40 watts. They Dropped the Ehiem pump and went to 2 pumps now pulling 30 watts each for a total of 60 watts to produce 77SCFH.

The water to air ratio is 66% 2000 lph plus air to 3000 lph water. i think its like a skimmer neck without the body. from my math i figure it has about a 15 second dwell/contact time in the 9.5" body. i think that about the same as or more than most beketts, and the same as or a little less than most NWs.

heres a video. http://www.it-kontaktmanagement.de/bm_action.swf and here is their web site
http://www.atiaquaristik.com/index.php?id=91,0,0,1,0,0

RichConley

10/04/2006, 08:57 AM

<a href=showthread.php?s=&postid=8272575#post8272575 target=_blank>Originally posted</a> by Zephrant
It is always tough to measure skimmer performance- I'd would like to mention that raw air flow is not very meaningful without considering the water flow too. While there is a maximum amount of air that can used and still get "foam" (and not just a top-off-of-the-blender effect), some designs can run just fine on far less than that maximum number. I'd suggest that a SCFH/GPM measurement might be useful, but that does ignore the system water volume which I feel has a far greater impact as the well-being of the inhabitants.

Zephrant, while Beckett users always bring up "water flow" as a positive, I've seen nothing that justifies that.

My skimmer is a recirculating 8" needlewheel that pulls about 30scfh. I move roughly 150gph through it. When I increase the water flow, I get less skimmate, period. Its not a turbulence issue(water is injected before the pump, not into the cone like most recircs), its the decrease in contact time.

DocG

10/04/2006, 09:41 AM

Al,

I plan on giving Euro-Reef a call today about the new impeller. Hopefully I will get them soon.

My Beckett skimmer is a MRC-3 with a 24" extension on it giving it a total height of 56.5". It is run by a panworld 250PS pump.

I dialed in the skimmer before I got my airflow meters and was very comfortable with the settings. When I tried to run it with the increased air it reacted and performed much differently then the old way and I just gave up and returned to the old way of doing it after about 2-3 days of tinkering with it.

I found the Sweet Spot at 32 scfh and it is great. By sweet spot I mean that the thing skims like a machine with no tinkering at all. When you find the sweet spot (it can take a while) then you generally don't want to change it.

I am sure that I can set this thing up with a full amount of air, I just need more patience.

I also clean the beckett when I see a decrease in airflow. In my experience it is every 3-4 months at the most.

Zephrant,

Is it water flow that we want to measure or water volume?

It seems to me that you want a certain air/water ratio and it wouldn't matter how fast the water was entering and exiting you will always have the same volume. A faster water flow will give you a higher turnover (which is good) and a slower water flow will give you a higher contact time (which is good).

alwest45

10/04/2006, 11:31 AM

<a href=showthread.php?s=&postid=8272575#post8272575 target=_blank>Originally posted</a> by Zephrant

As mentioned above, power draw is a valid concern, but as I've not seen the math posted yet, how about this:
165 watts is 1.375 Amps at 120VAC. Running 24/7 that is 27.7 K watt hours per week, or about 1441 KWH per year. I have dirt cheap power (less than $0.05 a KWH), so it would cost me $1.39 a week or $72 per year to run a 165W skimmer.

Wow, my little thread is getting the heavyweights to weigh in. I am honored. I'm also envious of your electricity rates. I think the national average is about 10 cents a KW so that's the number I use to do calculations. But I also noticed that my tank electrical usage is overwhelmingly dominated by my lighting and chiller. Switching to 250w HQI lights with better reflectors will do a lot more for my electricity usage. Now I'm breaking my own rule that I don't want to turn this discussion into an electricity usage discussion. I want to keep focused on which skimmer will do a better job of keeping my acros happy and colorful.

I do really like your point about not just focusing on air flow. The other things you mention ( Tank volume, Tank inhabitants, Feeding regime) are clearly very important but are not variables in my case (i.e. they will be the same regardless of which skimmer I choose). I'm going to do more analysis and try to factor in water flow and water volume and see what comes up. Does anyone know how to post charts and tables here? Do I first have to convert them to an image and then import the image?

Al

alwest45

10/04/2006, 11:54 AM

<a href=showthread.php?s=&postid=8274153#post8274153 target=_blank>Originally posted</a> by DocG
Al,

...
Zephrant,

Is it water flow that we want to measure or water volume?

It seems to me that you want a certain air/water ratio and it wouldn't matter how fast the water was entering and exiting you will always have the same volume. A faster water flow will give you a higher turnover (which is good) and a slower water flow will give you a higher contact time (which is good).

DocG, taken to the extreme this seems clear. If you had a very large volume of water in your skimmer (say 30 gallons) then you would get very good numbers if you weighted things by how large the volume was but if your flow rate was tiny (say 10 gph) then it seems clear in this example that's not what you want. I'm not sure I see what is wrong with focusing on water flow. Sure if the water flows too fast you'll miss some organics that you could have picked up if it was slower but you'll get another chance when that water flows through the skimmer again. It's almost like looking at your whole tank as the recirculation reservoir for your skimmer (rather than just the skimmer body being the recirc reservoir).

Now I'm going to step in it. I know sacred cows are off limits for some people. But as I think about this I'm not sure I get the whole recirculating skimmer advantage. Yes, the water stays in the skimmer longer with a recirc design but every loop through the pump destroys the old bubble (which carries the organics) and creates a new bubble which has to attract the DOC again. How is this better? I thought I saw an article recently (I think it was by Randy Holmes-Farley but it could have been someone else - if anyone knows I would appreciate a reference) that made the case that you need to pull the skimmer water directly from the water entry in your sump. They recommended that you minimize the dilution of your "dirty water just in from your tank" with the rest of your sump water. The point was that your skimmer does a more efficient job if you can send it the dirtiest water and letting already skimmed or algae processed water mix in with the dirty water will be less effective.

So imagine now that we view the sump and the skimmer as a single system and we use the sump to hold the recirc water for the skimmer. Doesn't this mean that you are going to be less efficient when you start skimming the "already skimmed" water? Wouldn't you be better off just sending the skimmed water back to your tank and getting more "dirty water" (not yet skimmed) to process in your skimmer?

Ok, there. I said it. I don't get the recirculation concept. I am about to jump on an airplane so any flames will not hit me until much later. I'm not trying to start a thermonuclear war. I'm just not sure I understand how recirculation in the skimmer is a big winner. Judging from the skimmer company offerings it seems like it is. But having to regenerate bubbles from already skimmed water doesn't seem like the most efficient approach unless your skimmer is undersized for your system and you know you can't really lower the overall DOC in your tank.

One final request. I know this topic will generate lots of handwaving. I know how to handwave too but that approach will be unsatisfying (at least to me). Does anyone know of real numbers or research that demonstrates that recirculation in a protein skimmer works better than just building a bigger/better skimmer. Because that's the tradeoff we are making. The skimmer companies charge more for the recirculation design skimmers (in many cases). For the same dollars we could get a bigger or better non-recirculating skimmer. Why isn't that the better approach?

I will change into my asbestos suit on the plane so I will be well protected when I next join this discussion.

Al

Roland Jacques

10/04/2006, 12:17 PM

Your geting into plumping issue with the dirtest water thing. You can plumb ANY type of skimmer to take water directly from the tank period, via the overflow. (In sump, recirc., nw, beckett, DD ANY skimmer) that just a simple matter of hooking it up that way.

Roland Jacques

10/04/2006, 12:42 PM

I think recirc vs non recirc is a little off topic but it your thread and you do need to concider the flow control that only recirc's offer.

Recir
Control, infinite flow control if you want to flow 10 GPH or 500 GPH you can do that. (remember water in = water out, so what the pump does with the water does not mater)
Less back pressure on pump allows it you pull a little more air in.
External installation. &
Less heat in system from submerged pumps
Easier plumping to direct feed the skimmer from the tank.

Roland Jacques

10/04/2006, 12:46 PM

Ooops]

RichConley

10/04/2006, 02:42 PM

Roland is on point here. In a proper recirculating skimmer, bubbles arent making it down to the pump input, so nothing is being "broken off a bubble". What recirculatign skimmers do is 1) create a much stronger counter current in the skimmer, and 2) allow you to tune water input and air input independantly.

Point 2 is huge. I run about 200gph from my tank to sump. Running 700gph on my skimmer doesnt give me any advantage. It decreases contact time, without giving me access to any dirtier water.

With a general non recirculating skimmer, when you reduce air intake, you increase water throughput, which plays havok with the levels in the skimmer. Theyre much easier to tune, and much more consistent when you seperate the two.

McCrary

10/04/2006, 02:43 PM

Zephrant- I can see how tank volume might affect the performance of a skimmer, but I can't see how it would be a consideration in design. Is there something that I am missing?

I would think that recirc would work very well for tanks that are adequately skimmed. The increased contact time would remove molecules more resistant to exportation. But you trade that for volume flow through. This would not be a problem if the skimmer was adequate for the bioload of the tank.

RichConley

10/04/2006, 02:52 PM

So imagine now that we view the sump and the skimmer as a single system and we use the sump to hold the recirc water for the skimmer. Doesn't this mean that you are going to be less efficient when you start skimming the "already skimmed" water? Wouldn't you be better off just sending the skimmed water back to your tank and getting more "dirty water" (not yet skimmed) to process in your skimmer?

Take that a step further, and think of the sump, skimmer, and tank as one system. See the point? Either way you're skimming diluted water.

I guess my thinking is this: the only place where I can really see an advantage to the "clean more water less well" over "clean less water more well" is in the situation where the skimmer is too small for the bioload.

In Escobol's papers, there much mention of certain things needing long contact times. High throughput skimmers dont have those contact times. A big, low throughput skimmer can pull out plenty of material, but also can pull out more of the "hard to get" stuff.

The point is, any decent skimmer is going to do a good job and pull out most of the waste, even with a low throughput. It just takes one with a really high contact time to pull out the tough to get last amount of waste, and I believe thats where recircs excel.

I think if you take a filthy tank, and put a beckett on it, it'll clean the tank up faster than the low throughput needlewheel will, but I dont ultimately believe that it will get it as clean in the end.

McCrary

10/04/2006, 03:01 PM

But what if a Beckett has the same contact time as the recirc. skimmer?

Zoom

10/04/2006, 03:11 PM

<a href=showthread.php?s=&postid=8276443#post8276443 target=_blank>Originally posted</a> by TurboSnail8898
But what if a Beckett has the same contact time as the recirc. skimmer?
The only way to do that is with a recirc beckett skimmer , Now you need to add water to the skimmer .
I saw a MRC Recirc skimmer very large and bulky, they did not get to papular did they ?

BreadmanMike

10/04/2006, 03:11 PM

Let's not forget the Recirc beckett.... :)

RichConley

10/04/2006, 03:13 PM

recirc becketts are fine, but you have to rememeber that it really doesnt matter how the bubbles are made....

and you can make significantly more bubbles for less watts with a needlewheel.

McCrary

10/04/2006, 03:16 PM

Than its seems NW skimmers have the advantage. Becketts put a lot of water through them, but don't get the molecules that are hard to export. You can put just as much water through a NW by increasing the pump size.

hahnmeister

10/04/2006, 03:20 PM

Ill throw this out there though... downdrafts and becketts are much better for raising ORP than NWs are.

Zoom

10/04/2006, 03:22 PM

Roland Jacques

10/04/2006, 03:47 PM

deleted

WarrenG

10/04/2006, 03:56 PM

Alwest, et al,

I tested a OR 2700NW with adjustable air input to the intake side and it produced plenty of air, and I could tune the flow through rate with a valve before the intake, and adjust the amount of air with a speedfitting.

I thought the OR2700 was too noisy so I experimented with a Kent venturi before and after a Mag3 and Mag5. The foaming was very similar to the OR, but with less pump noise and I think less watts (as if I care about 20-40 watts in an entire house!). The air input (venturi) works great whether I adjust the flow rate from 100-150gph (Escobal suggests ~120gph for my tank).

I bored out the venturi slightly to optimize it for my flow rates.

I didn't like the noise of a Beckett.

Manufacturers pay a few dollars for a Beckett, and it's in vogue now. They pay $40 more for a Mazzei venturi and they're old news.

No need to re-circ if you get enough air into the water before it enters the reaction chamber the first time. Contact time is a function of how fast water goes from the entrance to the skimmer to its exit. Re-circ doesn't change that. Too much turbulence in the chamber is not all good. Not hard to make enough turbulence with a decent CC anyway.

saveafish

10/04/2006, 04:03 PM

kool thing with becketts you can push them a lot harder if you want to upgrade to a larger tank just add a bigger pump

I put a 1 1/2 hp, seahorse on my MRC-8448 to see what it could take it works good but the air intake sounds like a B-2 bommer taking off (what a suck zone)

daytonreefRob

10/04/2006, 07:21 PM

One of the main things I have noticed about the beckett vs needlewheel debate is the pump size - in general needlewheel pumps are small and beckett pumps are hefty. Just wait until Reeflo releases their needlewheel impellers for their pumps. I think this will change many of the opinions of what a needlewheel skimmer can do.

Up to this point, there has been some sort of a line that NW units were good for (somewhere about 300 gallon system), after that it is generally considered that a beckett driven unit would be better suited to handle the system.

Another thing to think about, the Reeflo Dart is a flow rated pump, and it only draws 160 watts. This is a far cry from an Iwaki pressure rated pump.

Zephrant

10/05/2006, 12:12 AM

Here is a chart I post every six months or so:
http://www.barraquatic.com/rc/Beckett-2.jpg

That shows the water flow vs. air flow though a Beckett in to free air. For a Becket skimmer with the injectors mounted up above the water level, this can be used to approximate the water flow if you know the air flow, and vice versa. But you do need to match the test conditions- 3/8" tubing and valves or at least dual 1/4" inputs.

I don't have pump profiles though a skimmer available- I'd like to get watt, gph and scfh readings for various pumps some day.

Rich- Definitely room for debate. Is a 10x tank turn over though your skimmer per hour better than a 1x turn over? Answer: Depends on way to many other variables to have an single answer. ;)

As you know, Beckett skimmers are geared for high tank turn-overs, and shorter contact time. Most all aspirating skimmers are the opposite, which is part of the reason they perform differently. There is no doubt that both types work well, and both types have strong believers.

I believe your observations, but can't offer a theory without seeing the unit in action and pondering. I've not spent much time experimenting in what I consider "low flow" skimmer designs, as my personal preference is in high-flow skimming- Not for the skimming performance alone, but for the extra aeration and "safety margin" that it gives.

Let me expand on that a little- High air/water flow skimmers do have one clear trait- they can pull lots of "stuff" out very quickly. This is best observed by adding a foaming agent to your tank (Prime, or most antibiotic medications). The big skimmers will happily pull out gallons of water per hour- On the floor if you don't have an auto-shut off collection container. But this same feature is of tremendous benefit if something nasty happens in your tank- like a spawning event. IMHO, having a big monster skimmer sitting at the ready to pull out that kind of pollution quickly is very much worth the cost of power to keep it on "standby". It's the same reason I drive a V6 instead of a more standard 4 cyl in that car size- The power is there when I need it, even though it costs me more to run.

I run a skimmer that is more at home on a 500g tank, on my 200g system. so I'm also a believer of the "can't over skim" camp. :)

Doc- Water flow is just a way to get flow divided by volume, to give your contact time. Sometimes having the same data expressed in different ways can help with the analysis.

Al- I don't like to admit how low our power is up here- Too many people want us to pay more so they can pay less. :) I don't like to "waste" power at all, but the power draw of my skimmer is very low on my list of concerns about my tank. To post charts, you need to export to a JPG from Excel or something similar, then you can post it.

Turbo- The point I was stretching for was that perfectly optimizing a skimmer purchase decision by using one feature (air flow for example) can turn out to be insignificant when compared to other variables in an entire system. The "best" skimmer can't be determined without knowing all the above information.

Rich- The big oversight that Escobal makes is here: Page 84 ...experimental observation indicates that two turns a day will suffice to process the water." (Aquatic Systems Engineering, by P.R. Escobal, Second Edition)
He then goes on for 30 pages designing the perfect skimmer for that assumption. What are his qualifications to make that observation? Where is his PHD in Biology? How many years has he kept reef tanks, and how many different "turns" did he try on those tanks to come up with the magic number "2"?

Escobal's book is great on theory and numbers, but he looses all credibility when he fails to explain why 2 is the magic number of turns per day. That said, there is still lots of good information in there, and I recommend that everyone pick up a copy someplace. But look at it skeptically- Escobal is a great physicist, but I've never seen a shred of evidence that he ever kept a large reef tank, much less did the kind of testing necessary to come up with that kind of data.

Zeph

Roland Jacques

10/05/2006, 01:20 AM

Zephrant
Good info, thanks for the chart, pressure would also be helpful in determining what pump can achieve what air/water flow.

I did want to vistit something you mentioned earlier.

“Dwell time- skimmer water volume, divided by input water in gallons per second gives the number of seconds that the average water particle will be "in play" in the skimmer. This is a very rough average, as it depends greatly on the skimmer design. Picture a long tall counter-current tube, vs. a short square box. Both could have the same dwell number, but very different performance. But for similar physical designs of skimmers, this is a good measurement.”

This is true, because the taller one will give more “hits”(air bubbles coming in contact with waste), but skimmer shape needs to be weight against the other factor that causes hits, that's air volume. Which one gives more hits, a tall skimmer or a short skimmer. If they both have the same volume with the same air Ratio. Like you say, everyone knows it is the tall one. If both skimmers have the same total volume and the tall one is receive 20 scfh of bubbles and the short one is receiving 30 scfh. Well it no longer as clear. As technology continues to improve (smaller, cheaper, pumps ability to provide more air per volume and watts) this will continue to have to be revisited when we choose a skimmer.

Its been clear with few exceptions that Becketts have had higher hit counts, and NW had higher dwell time. NW have been trying to increase thier Hit counts with more air, and Becketts are trying to increase their dwell time with bigger/add on body chambers. But the times their a changing, 60 watts 75-80 Scfh.

I think Doc g has it right, have one of each if possable. As rich pointed out, one for stubborn stuff, and one that processes more water faster. (forget about the ORP thing hahn, lol)

I agree with Doc G said if I would to choose one for a home aquarium I to would choice the one that scrubs better. If I had a store or big holding system with lots of rapidly changing bio-loads… then the high flow Beckett would be my choice. Ether way they both can be good skimmers.

And no one mentions Down Drafts skimmers anymore why is that? They seem to be even futher towards the faster prosesing of water than the becketts. If a little faster is good then is a lot faster better?

So is this it? On one side we have NW / airstone type skimmers long dwell time and on the other we have Down Draft type short dwell time skimmers. Then everything else falls inbetween.I wonder where Tunze Doc skimmers fall.

JC VT

10/05/2006, 08:06 AM

Roland, or anybody else,

Can you guys elaborate on what different kinds of 'stuff' there is? I'm under the impression that any amphipathic molecule will interact with an air/water interface. It seems a little weird to say that one elaborate bubble making machine will pull different stuff than another.

Roland Jacques

10/05/2006, 09:18 AM

JC VT the word i used was Stuburn. Not different.

I can find you a link on this later if you want. I think Randy has a actical that touchs on that.

alwest45

10/05/2006, 12:22 PM

<a href=showthread.php?s=&postid=8276561#post8276561 target=_blank>Originally posted</a> by hahnmeister
Ill throw this out there though... downdrafts and becketts are much better for raising ORP than NWs are.

Hahn, I have heard this before about becketts being better for improving ORP but I'm not sure I understand it. Do you mean that if you have a low ORP a Beckett will raise it faster. I guess I can understand that in that the Beckett will process the water faster and therefore improve lower water quality faster? From this same perspective it would seem that if I am overfeeding my tank then a beckett would more quickly clean it up and get it back to the nutrient poor state I’m trying to achieve. Does this match with your understanding?

Roland, you are right. Recirc vs. circ should probably be a different thread. I was surprised there wasn't more excitement - probably means I didn't express myself well enough. If anyone thinks they really understand the science behind recirc (and I mean more than giving you better water flow control) feel free to pm me for a little offline discussion. I would also be interested in any articles on the more stubborn things that need longer contact time. Randy recently did a “What is Skimming?” article and I didn’t see any specifics on this. I’ve also looked through The Reef Aquarium volume 3 (a great book btw) and didn’t see much on that. I can intuitively understand why that might be the case but Zephrant’s point about Escobar’s assumption makes me wonder if anyone has really done the research to figure this out or are we all making assumptions. It’s also helpful to know how much longer it takes to get those stubborn molecules out of the water. For all skimmers, the window is pretty close. Is an extra 30 seconds good enough to get the stubborn ones? How about 3 minutes? What about 10 minutes? If it takes too long then no skimmer is going to get them. It would be great if someone had a chart that showed what percent you could get out by exposing a certain amount of water to a certain amount of bubbles by time, i.e. what percent you get out in 10 seconds, in 20 seconds, etc. up to 90+% removed. Has anyone every seen anything close to this?

WarrenG, I don't think the skimmer manufacturers decided to select Becketts just because they were in vogue. I tried to pick a list of the very best skimmers out there and I didn't see a pure venturi skimmer to add to my list. Do you know of a pure venturi skimmer product that can run with the very best of the needlewheel and beckett skimmers? For the same reason I didn't include any plain downdraft skimmers (shooting water against plastic media to make bubbles). It appears to me that they have been surpassed by the good beckett skimmers in terms of performance.

Zephrant, your last post was very helpful and has a wealth of new understanding (for me) in it. Thanks too for the tip on how to post charts. The thing about your chart that was confusing to me is that you used a Sequence 3600, which is essentially the Dart pump and maxes out at 12’ of head (just like the Dart). The Dart has a bad reputation for driving beckett skimmers (not enough head) but yet you show it doing almost 70 scfh. I believe your numbers but two questions arise. How can a 3600/Dart pump generate 68 scfh and why are the Austin Oceans guys (I think you’ve heard of these guys) quoting only 45 scfh for their single beckett skimmers on their website. Why don’t you tell them how to get 68 scfh with a Dart and maybe I’ll switch back from the ER RC500 to their beckett skimmer?

Let me try out some more analysis. If I try and compare a RC500 (with 2 new Gen-X 4100 pumps plus an Eheim 1250 to feed the skimmer (gravity feed for the skimmer doesn’t work in my setup) vs. the AO Foaminator MAX 5000 (Sequence/Reeflo Tarpon pump) and I want to understand the impact of skimming a 240 gallon tank and can compute a number of relationships. If I want to think about how long it will take them to skim the entire tank I first decide on my effective throughput:

Eheim 1250: 317gph*.8 (for head loss) = 253 gph (within the ER recommended 1-1.5x turnover)
Sequence/Reeflo Tarpon: 1440gph*.6 (more head loss) = 864 gph (within AO recommended minimum 800 gph per beckett numbers)

Does this look ok? I am estimating the head loss for feeder pump on the ER and estimating what the head loss is through the beckett? If anyone has better estimates please let me know.

Now, I can do some calculations on how long the skimmers will take to skim 240 gallons:

ER RC500
240/253 = .94 hours to skim one pass of the tank
24 hrs/.94 = 25.5 X turnover of the entire tank through the skimmer in a day
25.5 passes of the entire tank
25.5*240 = 6120 gallons skimmed (in a day)
(6120gpd*76scfh*24hrs)/1000=11,163 (airflow processed per day product?)

AO MAX 5000
240/864 = .28 hours to skim one pass of the tank
24/.28 = 85.7 X turnover of the entire tank through the skimmer in a day
85.7 * 240 = 20568 gallons skimmed (in a day)
(20568gpd*45scfh*24hrs)/1000=22,213 (airflow processed per day product?)

Now I’m not sure of this last “product”. More scfh applied to the entire tank seems like a good thing. It’s perhaps good now to consider the Deltec vs. the ER RC500 since they can both use the same Eheim 1250 skimmer feed pump and are similar designs of similar size. So the gallons skimmed per day will be the same. But I think the ER is probably doing a better skimming job because it processes more scfh for the same gallons per day.

If I do the same calculation on the Deltec AP902 I get:
240/253 = .94 hours to skim one pass of the tank
24 hrs/.94 = 25.5 X turnover of the entire tank through the skimmer in a day
25.5 passes of the entire tank
25.5*240 = 6120 gallons skimmed (in a day)
(6120gpd*56scfh*24hrs)/1000=8,225 (airflow processed per day product?)

This seems intuitively correct ratio wise when looking at just the Deltec and the ER. But I think I am missing something when comparing different style skimmers. I’m not sure how to use dwell time since a dual beckett has half the dwell time as a single beckett skimmer (same body size). Contact length seems like a good metric to include somehow but I’m not sure I understand how that would work for recirc skimmers. I’m reasonably comfortable with the pieces so far, gallons processed per day and scfh per day but the numbers seem to imply too great an advantage for the beckett skimmer. Any good ideas of other metrics and algorithms? Keep in mind that the obvious case of weighting how slow the water passes through the skimmer lets the needlewheel guys “beat” each other simply by specifying a slower feed pump so that doesn’t seem right. Maybe you have to look at scfh per water volume of the skimmer body to see how concentrated the airflow is with the water processed, perhaps including a component of contact length as a proxy for average bubble contact time (again not sure how this fits with recirc skimmers), i.e. how dense a concentration of bubbles you can achieve in a limited volume seems like an interesting metric and in that scenario longer contact paths should give better results.

ER recommends 1-1.5x turnover through their skimmers per hour. I wonder where they got that number? Is it just convenient or do they have some science behind it?

Some might say this is a hopeless quest and that this is too complex a subject to be reduced to a single number or two. However, there are some simplifying assumptions. First, I am certainly willing to limit this analysis to very good performing skimmers. So I can eliminate the pathological cases that might twist the results. Second, although some skimmers may perform better when slowing the water flow I don’t think I have too many qualms about letting skimmers that process water faster get higher scores. There are natural limits to how fast any skimmer can process water without failing (you have to get the bubbles into the water and then get them out of the water for return to the sump and this can only happen so fast) so even if you find you get better skimming by tuning the flow down slightly that still seems like a valid metric. Obviously a work in progress. Any advice or suggestions is welcome.

Al

RichConley

10/05/2006, 01:23 PM

Al, for what its worth, the ETSS 800 I had for a while was a much nicer skimmer than the dual beckett I played with.

alwest45

10/05/2006, 01:37 PM

<a href=showthread.php?s=&postid=8282727#post8282727 target=_blank>Originally posted</a> by RichConley
Al, for what its worth, the ETSS 800 I had for a while was a much nicer skimmer than the dual beckett I played with.

Can you tell me what brand beckett and what pump it was using?

RichConley

10/05/2006, 02:55 PM

It was an Iwaki 70, the skimmer was an no name brand, I honestly dont remember what. The design was the same as the better becketts though, just without all the bells and whistles.

WarrenG

10/05/2006, 05:00 PM

<a href=showthread.php?s=&postid=8282305#post8282305 target=_blank>Originally posted</a> by alwest45
WarrenG, I don't think the skimmer manufacturers decided to select Becketts just because they were in vogue. I tried to pick a list of the very best skimmers out there and I didn't see a pure venturi skimmer to add to my list. Do you know of a pure venturi skimmer product that can run with the very best of the needlewheel and beckett skimmers? Al

I really don't know the ready-made skimmers at all so I don't know if any use a venturi now. I tested the OR2700NW with and without the venturi and before and after that pump, and a Mag3 and Mag5 the same ways before settling on what works best for me-Mag3 after the Kent venturi (I bored it out a little).

When I consider the fact that most of these combinations worked pretty well I tend to doubt that a Beckett is so much better than a venturi that Becketts are all that should be used, just that Becketts are what companies want to use. Similar for NW. Company's try to convince consumers that their product is different from the competition, and that the difference(s) are worthwhile.

You do raise a good point, and that is, all the talk about the hardware tends overshadow the fact that more than one method will work really well, and attempts to objectively evaluate that would be useful for us.

The skimmate I get looks more like coffee than tea, and the volume is quite a bit more than the amount of food I put in the tank. Not sure if I'm getting out all I could but all seems good.

Zephrant

10/05/2006, 11:16 PM

Al- The test was just a Beckett plumbed with 1" line direct from the test tank, held at about 2' above the water level of the test tank (timed filling of a bucket was used for the GPH measurements). The biggest difference is that the test used larger air valves, tubes and flow meters. Since a Beckett needs to be restricted to run well, the 68 SCFH number is not "usable". In my testing, around 45 SCFH per Beckett has shown the best results. I don't have any numbers to give you describing why that works best, just my observations on my own systems over the last several years (however confirmed with many conversations with others running Becketts).

At first glance, your numbers look right- The perceived large performance imbalance in favor of the Beckett is countered somewhat by the aforementioned shorter dwell time. I think it comes back to the "gets lots out in one pass" vs. "gets less out per pass, but makes more passes". I suspect that if we could map the real "skimmer performance curve", we would see that it has a series of humps in it and you'd find top of the line skimmer styles at each high-point in the chart.

Rich- There is a series of mistakes a novice skimmer builder can make that can really ruin performance. I suspect you might be pleasantly surprised if you got to play with a current production model.

Warren- I can't speak for the other people, but in my case I could build any design that I wanted to for my own use. I chose Becketts because I felt they offered the best balance of performance vs. cost. A "Beckett" is just another venturi type, but happens to be optimized for lots of air intake from ambient conditions, under relatively low water pressure. There is nothing magic about them, it is just a very well designed device.

Again, I don't think there will ever be one answer to these questions- The leading skimmer types are "leading" because they all work well. If I had more money than time (and didn't want to DIY my own equipment), I'd have no problem running a Deltec, BK or other top of the line needle wheel skimmer on my own system.

Roland Jacques

10/06/2006, 07:35 AM

Alwest, your figures up top are not correct because their not base on the correct info. You can spend a lot of time trying to get the right info, but even then, it is not going to be very helpful in comparing different skimmer. If you just wanted to compare 2 identical skimmers then your air info COULD be very helpful in determining performance. But even then more air may impact foam stability and be counter productive in some ways.

I understand its can be confusing, looking at Recric skimmer when you have Becketts & In sump skimmers in your mind. That is one of the areas you messed up with your numbers. You are trying to make them harder than what they are (I did the same thing when I first started looking at them). Think of a recirc pump as just a "Airstone connected to an airpumps” the water flow is not relevant to any thing at all. Except unwanted extra skimmer turbulence. That is why some of your best skimmers Bubble king, Bubble master, and it looks that even Barr use turbulence diffusers to eliminate extra skimmer turbulence. The idea NW recic pump would not need any water movement at all. (Basically a maintenance free airstone)

The main goal of the recirc skimmer was and is to “slow down flow” (they really mean increasing contact time). The main reason people buy add on sections for becketts skimmers is to “increasing contact time”. The main reason people buy larger body skimmers is to “increasing contact time”. To think that “increasing contact time” (slowing down flow in NW) is not a plus is to ignore all of that. There are other factors that you can also conceder lots of them some are just theories. I got to say theirs probably more that we don’t know about skimming than what we do know. So we just compare and test better results = better results. Why? Like the ORP with the DD skimmers being higher than NW. Why does a Tunze with know dwell time work so good.

If you really want it figure out on paper what will give you best performance “hit numbers” will be the most helpful thing you could mathamaticlly figure out IMO. Much more than just air.

You are trying to put skimmer performance in a box. Unfortunately I don’t think this can’t be done with math and known factors. Allot comes from trial and error. Observation, isolating and testing, of piece parts and compete units give you probably some of the best info... testing using identical water is one of the best ways to get a handle on performance of skimmers.

Be warned, you are seeking a lot of skimmer info that’s great, but the long term effect can wreak havoc on your life. Your garage could end up looking like some kind of mad mans lab. You may just start buying skimmers just so you can test them. You may find yourself collecting skimmate from LFS… just to use it to test new ideas, ventures, pumps, impellers… without live changing varyeiables. not to mention the wife factor.

alwest45

10/06/2006, 09:49 AM

Roland, thanks for the details (and the pm). If I understand your point it's that recirc skimmers not not effectively increase contact time (talking about needlewheel skimmers here) but allow you more effective control over water flow through the skimmer (giving you independent control of airflow and waterflow). That was very helpful and I get it. What I don't understand is why slowing water flow through the skimmer is inherently better. The water inside the skimmer is "cleaner" than the water in my tank since it's already been partially skimmed. By slowing the water flow through the skimmer I am continuing to try and "clean" progressively cleaner water (the longer it stays inside the skimmer) and the water in my tank (the dirtiest water) is still sitting there and not getting any bubble treatment. If I understand you point it seems I can increase the performance on the RC500 I'm planning by switching from an Eheim 1260 to a 1250 feeder pump or even to a 1048. I understand how that will improve the water inside the skimmer but shouldn't I be trying to process the water sitting in my tank that looks like it needs processing more than the water sitting inside my skimmer?

The other point I don't understand now is the part about getting the "Stubborn" molecules out of the water. If recirc does not increase contact time, then how does it help with removing "stubborn" molecules? Or were you just suggesting that it's the contact time alone and recirc has nothing to do with improving removing the "stubborn" molecules.

If anyone has any pointers to papers or research about these elusive "stubborn" molecules I would appreciate a reference. I had heard that Escobal talked about them but it sounds like Zephrant has put that rumor to rest. Any other references?

This is harder than I thought it would be.

Al

RichConley

10/06/2006, 11:51 AM

What I don't understand is why slowing water flow through the skimmer is inherently better. The water inside the skimmer is "cleaner" than the water in my tank since it's already been partially skimmed.

Al, I guess this statement is the real point of contention here. If the skimmer can handle the load, the above really isnt all that true. Yes, there is a difference, but its so miniscule as to not make a difference, IMO.

From what I understand about the "stubborn molecules," basically, skimmers remove molecules that have both a hydrophobic and hydrophilic end. These molecues align themselves so that the hydrophobic end is against the bubble, and the hydrohilic is against the water. As you start getting more complicated molecules, it takes longer for them to spin, and realign themselves and stick to the bubbles.

In high flow skimmers, there just isnt time for that to happen.

Now, the question is, does that matter? Or are we looking at a situation where that complex molecule is goign to get broken up/eaten by bacteria, and then get skimmed out with the bacteria, or be easier to skim? I dont know.

Roland Jacques

10/06/2006, 12:00 PM

<a href=showthread.php?s=&postid=8288223#post8288223 target=_blank>Originally posted</a> by alwest45
Roland, thanks for the details (and the pm). If I understand your point it's that recirc skimmers not not effectively increase contact time (talking about needlewheel skimmers here) but allow you more effective control over water flow through the skimmer (giving you independent control of airflow and waterflow). That was very helpful and I get it.

What I don't understand is why slowing water flow through the skimmer is inherently better.

Ok, i think you do understand,
more air/ vollume =more hits
more time +more hits
It just means the skimmer is going to have cleaner water coming out of it.

The water inside the skimmer is "cleaner" than the water in my tank since it's already been partially skimmed. By slowing the water flow through the skimmer I am continuing to try and "clean" progressively cleaner water (the longer it stays inside the skimmer) and the water in my tank (the dirtiest water) is still sitting there and not getting any bubble treatment. If I understand you point it seems I can increase the performance on the RC500 I'm planning by switching from an Eheim 1260 to a 1250 feeder pump or even to a 1048. I understand how that will improve the water inside the skimmer but shouldn't I be trying to process the water sitting in my tank that looks like it needs processing more than the water sitting inside my skimmer?

and that is your million dollar question. NW vs beckett. what thru put is to fast? and what to slow? if you think speed is important go with beckett or Down Drafts. Down Draft skimmers are about twice as fast as becketts. so if speed of tank turnover is your main concern DD should be your choice.
when in doubt do like Doc G, he has one each nw gets smellier waste the other gets more waste..

The other point I don't understand now is the part about getting the "Stubborn" molecules out of the water. If recirc does not increase contact time, then how does it help with removing "stubborn" molecules? Or were you just suggesting that it's the contact time alone and recirc has nothing to do with improving removing the "stubborn" molecules..

Bingo.

If anyone has any pointers to papers or research about these elusive "stubborn" molecules I would appreciate a reference. I had heard that Escobal talked about them but it sounds like Zephrant has put that rumor to rest..

what rummor? Where & when did that happen???
lets ask this. Why do you think 2 top quailty skimmers, side by side the longer contact time skimmer pulls out darker smellier skimmate than the shorter dwell time skimmer? time after time
Any other references?

This is harder than I thought it would be.
:lol: yeah, but it gets the mind working. Thiers no black and white answer here.
Just differancent shades of blue.

Al

Roland Jacques

10/06/2006, 02:06 PM

"sounds like Zephrant has put that rumor to rest."

Oh I see, you were reefering to the recommended 2 times a hour turnover rate. good point sorry i missed that. I would agree with Zeph, it is kind of applied very commonly with skimmers without consideration the many skimmers performance variables and abillitys.

What is the name of that book?

Zephrant

10/06/2006, 06:29 PM

<a href=showthread.php?s=&postid=8279706#post8279706 target=_blank>Originally posted</a> by Zephrant
...experimental observation indicates that two turns a day will suffice to process the water." (Aquatic Systems Engineering, by P.R. Escobal, Second Edition)

That is twice a day for 99.99% of the water to go though the skimmer.

JC VT

10/06/2006, 09:42 PM

Another thing to keep in mind is that a decent tank to sump turnover is required to get heavier particulates to the overflow and to the skimmer. Then you would want a big enough skimmer to process all that overflow water.

hahnmeister

10/06/2006, 10:06 PM

That is exactly the opposite of the 'low flow' sump method that is used by many. You dont need high sump turnover, in fact it can work against you. A surface skimmer is for skimming just that... the surface water, to feed it to the skimmer. You can use a filter on a closed loop just as well if not better though to trap detritus.

JC VT

10/06/2006, 10:11 PM

Well I disagree with the lof flow sump method :)

And I disagree that you just want to skim the surface. I believe in getting bigger particulates like uneaten food out of the display and into the skimmer.

And detritus breaks down very fast, especially in a filter sock ;)

hahnmeister

10/07/2006, 12:55 AM

Well, I dont have many detritus problems, or phosphates, and all my tanks are 'low flow sumps'. I use sand cleaning critters, and even though the overflow isnt running like a toilet flushing with a 200watt pump, the in tank circulation is 40-75x turnover...enough to keep whatever it is in suspension long enough to get caught eventually.

As for targeting the surface, you should talk with the guys who do calfo style overflows for this very reason (and Calfo himself). The idea is this... proteins and oils build up at the surface of the tank. So if you target this area, and process it as best you can, you will be getting more with less. Low flow sumps have been shown to increase skimming efficiency with this. See, with a 'high-flow sump' you take in alot of the other water in the tank. This water is not as concentrated with proteins and oils as the top layer. And if you think that one or two passes through the skimmer is all you need, think again. Recirculating skimmers with 1000gph of mixing pumps can run only 200-300gph in throughput... to process that water over and over, getting out more. The ideal setup is a low flow overflow with the drain leading right into a recirculating skimmer where the water gets processed multiple times before returning to the tank. With a high-flow sump, the protein rich water is mixed with the other water, and all sent to the sump where most of it never even gets to go through the skimmer (a skimmer that prolly has less throughput than the sump some times... thats a waste)... simply passing by by and getting mixed back into the general volume... back to square one where it has to reach the surface again. So with a high-flow sump you need an even bigger skimmer to grab those organics because you have made it that much harder for the skimmer to get them. This might be great news for 'skimmer-heads' like Spazz (thats a compliment BTW), and Barr so he can sell a bigger skimmer, but its really overkill.

http://www.reefcentral.com/forums/showthread.php?threadid=550482

Roland Jacques

10/07/2006, 01:44 AM

<a href=showthread.php?s=&postid=8291373#post8291373 target=_blank>Originally posted</a> by Zephrant

That is twice a day for 99.99% of the water to go though the skimmer. Man i missed something somewhere 2 xs a day =99% :confused: thanks Zephrant ill go back & figure it out.

Hahn, now that's a great point. And it is right on point. Good link, thanks. I find myself stuck in old school thinking on that and i need to get with this info. You kind of have to look at insump skimmers a little differently when your sump flow is much lower than the skimmer's. I can see where in sump skimmers like Tunze, Euro Reef, Bubble Master... would work much better in the that situation.

Zephrant

10/07/2006, 10:21 AM

<a href=showthread.php?s=&postid=8293192#post8293192 target=_blank>Originally posted</a> by hahnmeister
Low flow sumps have been shown to increase skimming efficiency with this.
Hahn- I'll have to go check that thread, I've not yet seen any evidence of this idea and it is counter-intuitive.

Many of us don't have a sump only to feed the skimmer. My sump also has a large biological filter in it- Lots of eel grass, mushrooms and other stuff that pulls nutrients out of the water. (And the idea that these critters need some kind of "slow flow" to pull nutrients out of the water was debunked by Calfo long ago.)

So while only 1/2 the sump water goes in to the skimmer, the rest goes though the biological filter and is returned to the tank.

A "Calfo" overflow (basically a long overflow the length of the tank) is not needed if you have good sump flow. Look at your tank surface- if you have scum on it, fix it. If you don't, you have more than enough overflow to remove the surface layer. It really is that simple. Running a full back overflow then running a big sump pump is overkill. Not that it harms anything, but it is not buying you any "better" surface skimming.

Once the scum is off of the surface water, any more water being removed can be from the surface or any other level, it is all the same in our tanks.
<a href=showthread.php?s=&postid=8293192#post8293192 target=_blank>Originally posted</a> by hahnmeister The ideal setup is a low flow overflow with the drain leading right into a recirculating skimmer where the water gets processed multiple times before returning to the tank.
That setup is fine if you have a small sump, and slow flow though it. For people that use their sumps for detritus traps, mechanical filtration, or biological filtration, slow flow is not as efficient.

For reference, I'm calling "slow flow" about 300gph on a 200g tank (1 to 1.5x tank volume per hour). Where high-flow would be in the 5-10x tank volume per hour.

<a href=showthread.php?s=&postid=8293192#post8293192 target=_blank>Originally posted</a> by hahnmeister So with a high-flow sump you need an even bigger skimmer to grab those organics because you have made it that much harder for the skimmer to get them.
I can't agree with that one Hahn. Nothing is harder- diluting the proteins does not make each molecule less likely to adhere to a bubble.

HippieSmell

10/07/2006, 10:30 PM

Well I have an MRC-2 with an Iwaki MD55RLT. It's a little noisy, eats a lot of juice, and requires more maintenance than other skimmers. However, it processes about 900 gph, which isn't too useful in a sump with 200 gph going through it, but my sump is about 900 gph, so it matches nicely. Plus, it cost me $450. A NW that can perform as well as the MRC-2 would be a couple hundred more IME, plus the actual unit is a solid piece of equipment. Some of those NW though, they get this nice cappuccino froth, which really pulls out the DO. My beckett can't get the super fine froth, but it skims out inch long bristle worms. My favorite feature of the beckett is to be able to set it to ultra wet and skim out 5 gallons for a water change. You'll never get a NW to do that. All in all I love the beckett, but a Bubble King would stomp it for 10X the money. JMO

hahnmeister

10/08/2006, 10:13 PM

<a href=showthread.php?s=&postid=8294432#post8294432 target=_blank>Originally posted</a> by Zephrant
Hahn- I'll have to go check that thread, I've not yet seen any evidence of this idea and it is counter-intuitive.

It is counter-intuitive depending on what your beliefs are about skimming, and I didnt believe it until I stumbled into it and saw for myself by trying it. Proteins and oils naturally rise and build up at the surface of the aquarium. If this layer is slowly extracted and fed into a skimmer that can spend more time processing this (recirculating) targeted area, the benefit is that you are targeting what the tank has naturally gathered, and then dealing with it slowly and more thoroughly. Put it this way... if you were a surgeon removing a cancer, which works better? Zapping the whole body with radiation and hoping you made enough of an impact to the areas that really count, OR, isolating the area(s) in question and targeting these areas with a more intense treatment?

I think alot of people assume that their skimmers remove everything in their water in a single pass through the skimmer, when it may be something more like 10%, if that. The very proof is that recirculating/countercurrent skimmers produce more skimmate that is darker and nastier than their single-pass cousins. The extended processing time enhances what they can extract. For the most part, many proteins need more than what a single pass skimmer can deliver as far as exposure to be extracted. While there is some debate between what counts as dwell time, the proof is in the puddin'. If you intended have as efficient of a skimmer on a higher flow system, you would have to multiply your skimmer size by the throughput multiple. So that 50g reef tank would need a 6' tall, 12" diameter (just a guess) skimmer to provide all that water with the same percentage of extraction compared with a regular sized recirc skimmer running 1.5-2x turnover.

If you think that getting more water through the skimmer improves its efficiency, then by all means a high-flow overflow and skimmer are in order, but science has so far suggested otherwise. Its not the amount, but the amount of time spent inside the skimmer that counts. By making the water stay in the skimmer for 50-100 seconds, or even more, you are capturing that many more nutrients. If you look at it this way, its no longer counter-intuitive.

Many of us don't have a sump only to feed the skimmer. My sump also has a large biological filter in it- Lots of eel grass, mushrooms and other stuff that pulls nutrients out of the water. (And the idea that these critters need some kind of "slow flow" to pull nutrients out of the water was debunked by Calfo long ago.)

I agree that refugiums do need good circulation. It seems everything in our systems benefit from more flow, even macros and grasses. But this circulation doesnt need to come from the overflow. A low flow sump can easily accomidate a refugium. A powerhead inside the refugium will recirculate the water in the fuge and provide the flow needed. The higher flow aids in resperation, and if you think that mushrooms, xenia, grasses, etc, are able to grab nutrients in one pass as it flies past through a sump... well... you know its not possible in the first place. If the refugium's turnover is only 1x or 2x the tank capacity per hour, its hardly going to starve for nutrients to export.

So while only 1/2 the sump water goes in to the skimmer, the rest goes though the biological filter and is returned to the tank.

A "Calfo" overflow (basically a long overflow the length of the tank) is not needed if you have good sump flow. Look at your tank surface- if you have scum on it, fix it. If you don't, you have more than enough overflow to remove the surface layer. It really is that simple. Running a full back overflow then running a big sump pump is overkill. Not that it harms anything, but it is not buying you any "better" surface skimming.

Most Calfo overflows are designed to provide better surface skimming to those who intend to run higher flow overflows but still want to grab as narrow of a slice of surface water as possible. 200gph in a 200g is enough to remove a surface layer and hardly requires a 60" long overflow. So the Calfo overflow is by definition to deal with higher flow overflows and still target the top most layers. I would go so far to say that a calfo overflow and low flow sump are mutually exclusive methods. Running a low flow overflow/sump on a calfo might leave you with parts of the overflow running dry.

Once the scum is off of the surface water, any more water being removed can be from the surface or any other level, it is all the same in our tanks.

But all that extra water you are running through the overflow means you need that much larger of a skimmer to get the same contact time and efficiency as a lower flow setup. Lets assign some random numbers to illustrate. If the surface layers contain 80% of the proteins in the tank, heck, even just 50% say, and skimming this water alone would give you a 60 second exposure time in the skimmer, you would have a very nice removal rate. If, OTOH, you had not only this concentrated layer, but 6x that flow running throught the overflow, now you have that potential skimmate that is getting mixed back in with the general water volume. That 60 second skimmer exposire time just dropped to... what... 10 seconds? And in that extra 50 seconds the remaining potential just gets blended back into the general body of water and sent back to the main display where it has to find its way to the overflow again, and again, and again...

That setup is fine if you have a small sump, and slow flow though it. For people that use their sumps for detritus traps, mechanical filtration, or biological filtration, slow flow is not as efficient.

You can run HUUUUGE sumps with a low flow sump/overflow. Look at DNA's monster TOTM. http://www.reefkeeping.com/issues/2004-12/totm/index.php Its 300g, with a 100g sump, fuge, etc, and only a 100gph overflow. The throughput of a sump doesnt limit its volume at all. The slow flow provides great detritus settling, and plenty of mechanical polishing and chemical exposure (phosban only needs, what, 100gph to take care of a large tank... that should tell you something, and look at how effective a calcium reactor is despite its low throughput). I find that the overflow rate is easily compensated with having decent circulation inside the tank, and while more flow from the sump return in this case doesnt hurt, having good circulation in the tank means that detritus will still be prevented from settling and eventually make it to the overflow. I have seen high flow overflows with plenty of detritus pockets in them simply because the flow in the tank was not effective.

For reference, I'm calling "slow flow" about 300gph on a 200g tank (1 to 1.5x tank volume per hour). Where high-flow would be in the 5-10x tank volume per hour.

I can't agree with that one Hahn. Nothing is harder- diluting the proteins does not make each molecule less likely to adhere to a bubble.

Not at a molecular level, but it does mean that for a given size skimmer, you just lowered the exposure time and therefore the amount of skimmate it can remove in one pass. Its the concentration that you are messing with here. A low flow overflow uses the tank's surface kind of like a 'pre-filter' for organics that are attracted to it. Dont get me wrong, if you took that 1.5-2x the tank capacity suggestion for a recirc skimmer and upped it by 5x, so for a 200g tank, you would have 1500-2000gph going through the overflow, you could then increase the capacity of the skimmer to handle 1500-2000 gph of throughput and have the same thing... but then you are talking one HUUUUGE recirc/countercurrent skimmer.... 1500-2000gph would make something like a 6-8' tall 12-18" diameter recirc skimmer... which is often the case it seems. Reefers are running more through their sump, with less time for a skimmer to process the water, so they end up buying massive skimmers to compensate. I would say that running a low flow sump/overflow with a recirc skimmer should halve the size of the skimmer you need because you are making it that much more effective.

But hey, the proof is in the results. Many European reefers set up their systems like this, and many here on RC who have tried it have reported increases in quality and amounts of skimmate from their skimmers, even non-recirculating models, simply because even a single pass skimmer, if set up with its own sump section, ends up recycling the water multiple times if its throughput is 600gph and the sump is only passing 200gph.

I compare it to reading a book. Imagine you can read a book in 2 hours and get 100% of it. Great. Now, imagine you only have 10-20 minutes to read that same book front to back... how much are you going to get out of it? How many times are you going to have to read it for 10 minutes before it starts to make sense? Going back, trying to rethink everything and remember where you were. I suppose you could argue 'whats the big deal?', if it takes me one try for 2 hours, or 8 times at 15 minutes a pop? Well, its still speed reading. Escobal and others suggest a 2 minute dwell time to extract some of the tougher to attract proteins. Just like reading the book... speed reading still means you arent as thorough and there are going to be some areas that you will skip no matter how many times you read that book front to back because its too short of a time. Add to this the overflow then... this is like reading a book, but knowing where all the good parts are that really count. You can read those areas alone and be done reading in an hour.

At least, thats my take on it.

JC VT

10/08/2006, 10:27 PM

Proteins and oils naturally rise and build up at the surface of the aquarium.

Protein skimmers take advantage of this interaction. Which do you think hold more protein/oils... the surface scum or a chunk of fish poop/detritus? If you had a choice, which would you choose to get out first? And it's not like you sacrifice surface skimming with higher sump turnover. Most people, regardless of sump flow, have overflows that take water from the surface.

If you think that getting more water through the skimmer improves its efficiency

Always effective before efficient. No one doubts that darker skimmate is more concentrated and therefore more 'efficient'. If I scrape the mold off of old bread and harvest it, it's more 'efficient', but I'd rather throw the whole moldy loaf out.

I think wet skimming gets more out, it just looks less efficient because the 'stuff' (detritus, uneaten food, snail poop) hasn't decomposed yet (kinda like partially molded bread). I think the dark stuff is stuff that has already decomposed.

JMO...

hahnmeister

10/08/2006, 10:39 PM

Okay, I should have added: what if the skimmate was darker AND in the same volume or greater? To me, wetter skimmate doesnt mean much if it only contains as much as the smaller amount of dark skimmate. Its just more water.

When I converted one tank from a 1000gph overflow to 200, the skimmer still made as much gunk, it just was coffee compared to tea.

I dont know that lighter or darker skimmate means anything with regards to how decomposed the skimmate is though. Not that I have an opinion either way (well, just that darker means alot of other things besides how old the poop is), but one could argue that the older the poop/protein is, the lighter it would be because bacteria would have a longer time to start processing it and breaking it down into less harmful compounds. Its like saying Milorganite is worse than raw sewage because its been around longer. I can back that up by citing the nitrogen cycle and tanks that dont use skimmers as evidence. The longer the waste is in the system, the less harmful it becomes due to bacteria... so to say that dark skimmate is just that... I dont agree. If you take that old pooh, sediments, mulm, and detritus and stir it up, then you would expect more dark skimmate to be produced... but every time I 'stir up the crap' in my tanks, the skimmate is anything but dark.

As far as which I would rather process... fish pooh or oils and proteins... well... This gets into what you expect from your skimmer. If you intend to use your skimmer as a means of blowing hard particles out the top (semi-mechanical filter), then I agree, but that desire goes back to the debates on what skimmers really remove, and if those things should even be removed. There CAN be such a thing as overskimming depending on what your goals are. If you dose phyto and an hour later your skimmate turns green... what just happened? What do you think happened to the phyto your tank has made? Was removing that phyto good or bad? Some would argue that this is good, that total organic extraction 24/7 is better, and the only phyto/rotifers/etc that the tank should get should be from scheduled feedings. I dont agree with this 100%, and see the counterpoint that when you look at what corals feed on, its really the mulm, detritus, proteins, etc (and the phyto and pods that feed on that) removed by skimmers that corals would like to eat. There are those that argue skimmers remove more beneficial things from the water than bad... and being that the natural ocean doesnt have skimmers, I agree. Then again, the ocean doesnt have the high fish concentrations that so many reef tanks do... so I also agree with the pro-skimming POV. The oceans have unlimited amounts of pods that feed on detritus w/o the concentration of predators that our captive reefs have. Skimmers were intended to extract organic chemicals, so if you now use one to remove hard particles... thats up to you. I dont see this within the usual or intended scope of skimmer operation. Besides, fish poop is what my sand sifters need to stay alive, and sooner or later that poop will give off its oils and proteins for the skimmer to capture, leaving the nutrients that my sand dwellers want to have their fun with anyways. I suppose Im not really 'detritus paranoid'.

JC VT

10/08/2006, 11:17 PM

Hahn, it looks like you are up late like me :)

what if the skimmate was darker AND in the same volume or greater?

It's a big what if. I don't think people who skim dark have an equal volume as those who skim wet. I can look at my skimmer now and say that the cup would fill up MUCH more slowly if I skimmed dry.

If you take that old pooh, sediments, mulm, and detritus and stir it up, then you would expect more dark skimmate to be produced

Then it looks like it hasn't broken down yet.

IIRC healthy stony reefs have extremely low concentrations of dissolved organics, but high concentrations of available foods. I think this is a good model to follow.

Besides, fish poop is what my sand sifters need to stay alive, and sooner or later that poop will give off its oils and proteins for the skimmer to capture

Ecological rule of tens :) Your sand sifters can only take 10% of the detritus/whatever as food and then excrete the other 90% out as more detritus. Detritus eating organisms just don't take up detritus and then not poop. They poop too.

hahnmeister

10/08/2006, 11:56 PM

<a href=showthread.php?s=&postid=8303315#post8303315 target=_blank>Originally posted</a> by JC VT
Hahn, it looks like you are up late like me :)

yep, you get my last 1/2 hour here before bed...lol.

what if the skimmate was darker AND in the same volume or greater?

It's a big what if. I don't think people who skim dark have an equal volume as those who skim wet. I can look at my skimmer now and say that the cup would fill up MUCH more slowly if I skimmed dry.

Oh, I totally see where you are coming from. Most of the time when people change from wet to dry skimming all they are doing is adjusting the skimmer's water level. Im talking a change on a much larger scale though... making the skimmer recirculating (more CFM's), feeding the overflow water directly to the skimmer, and slowing that rate down. This will make a much larger impact... not even that the result is dryer or wetter, I know its an instant association for most but in this case I really mean just darker.

If you take that old pooh, sediments, mulm, and detritus and stir it up, then you would expect more dark skimmate to be produced

Then it looks like it hasn't broken down yet.

Oh, come on! Its been sitting at the bottom of my tank for months already! If its going to take longer than that, you really dont have a case here because rather than use the skimmer Ill just suck it out when I do a water change... :lol: Im just going to say I dont think darker means older here.

IIRC healthy stony reefs have extremely low concentrations of dissolved organics, but high concentrations of available foods. I think this is a good model to follow.

It seems sound, yes. So in that case, we should leave things that these coral's feed on, or things that the things feed on that the corals feed on... which is what skimmers remove. Wait a second...

Besides, fish poop is what my sand sifters need to stay alive, and sooner or later that poop will give off its oils and proteins for the skimmer to capture

Ecological rule of tens :) Your sand sifters can only take 10% of the detritus/whatever as food and then excrete the other 90% out as more detritus. Detritus eating organisms just don't take up detritus and then not poop. They poop too.

The ecological rule of 10's >>> "Only 10% of the energy in a trophic level is passed on to the next trophic level." Nice try there, but you are interpreting it backwards I think. Conservation of energy and mass would show this to be false in a balanced eco-system (they cant poop more than they take in, lol), but the idea comes from the notion of the food chain resembling a pyramid where the net weight or number of organisms that are needed to support the next level up on the food chain is 10x. "The 90% energy loss at each trophic level goes to the metabolic needs of the organisms at that level." So if a sand sifter takes in 1 pound of poop, its going to process 90% of the energy from that poop before it passes (in theory). The net result is still less poop. Lol. Sorry, Im having giggles as I type this thinking of starfish with constipation problems... I think its just best to say that the ecological rule of 10's here doesnt apply. If you read the rule closely, "Nutrients behave quite differently than energy; they tend to cycle and recycle within ecosystems". So in effect, you have used the rule of 10's as an argument for not skimming all together...lol. Here are the details in case someone wants to know... http://www.uncg.edu/bio/ConBio105/info/TrophicLevels.htm
If the rule applied as you say, the world would be a never ending stockpile of crap... Worms, snails, starfish, etc... they do break down the waste of other organisms and convert it to a 'lesser evil', or food for the next organism FWIW. Sure, its still detritus, but with less phosphates, less proteins, etc. I suppose you meant that its 'more detritus, less nutrients'... well... isnt that what we want? Besides, the more they deal with it, the closer it is to being completely broken down into nothing but neutral sediments, or food for denitrification.

"Nutrients behave quite differently than energy; they tend to cycle and recycle within ecosystems". The very idea of NNR proves this to be true. Most of the organisms that eat detritus and waste from the reef (okay, now we are getting into that area where the argument is 'what is waste?' as one organisms waste is another's food)

I dont mean to poke fun if this reads like I am, Im really not. If anything you are sending me off to sleep with funny images in my head. Im imagining 'what if it were true' and thinking how funny it would be to see a snail needing turbo-lax.

JC VT

10/09/2006, 11:47 AM

you really dont have a case here because rather than use the skimmer Ill just suck it out when I do a water change...

What case did I have? I wasn't aware that I had one regarding siphoning vs skimming.

we should leave things that these coral's feed on, or things that the things feed on that the corals feed on... which is what skimmers remove. Wait a second...

You're not implying that we should run skimmerless to 'leave things that corals feed on' right? Why run a skimmer in the first place?

Worms, snails, starfish, etc... they do break down the waste of other organisms and convert it to a 'lesser evil', or food for the next organism FWIW. Sure, its still detritus, but with less phosphates, less proteins,

Why leave rotting detritus in the system in the first place? LOL
Before it gets to your starfish, it's being decomposed by bacteria. After your starfish poops, it's being decomposed bacteria. Why have an army of detritus eaters that just adds to your bioload?

So in effect, you have used the rule of 10's as an argument for not skimming all together...lol.

Not really :) It supplements my argument perfectly. I prefer to remove the food source and cut off the rest of the organisms from their food source.

hahnmeister

10/09/2006, 12:08 PM

1. No big deal, you just mentioned that the organic matter must not have been broken down enough to produce the darker skimmate... and my response was... gee wiz, its been there for a couple months now! How much longer should I need? OR, if thats the case: that it takes that long for detritus to give off the organics that make darker skimmate, then just forget the skimmer all together and Ill just siphon rather than skim.

2. Many people do run skimmerless, yes, that is the implication. Im just saying, its a contradiction.

3. why not leave it in the system then? one organism's food is another's waste. For a complete ecological cycle in our reefs, removing anything would seem a bad idea. It is however impractical for people with mini-reefs because there just isnt enough room for everything needed. You say 'waste' and 'danger', I say 'food' and 'more diverse ecosystem'.

4. so you want to starve your corals except for the manual feeding you give them? Ok, I see how you like to run your tank. You are in the 'export everything' crowd. Nuf said. Im not, thats all. Heck, I turn off the skimmers 3 days out of the week for plankton/pods/etc to do their thing and I havent had a problem. I have had a remote plenum tank, DSB, BB, etc. I currently run a combo of skimmers and fuges with macros, and try to apply 'just enough' of each branch of thinking to get a balance within the reef. I myself dont think of my skimmer as a mechanical filter... there are plenty of other things that do that, including the critters in the tank that would love a fish-poop to feast on for a day.

Roland Jacques

10/14/2006, 01:59 PM

Old poo, new poo, brown poo, blue poo.
Who knew, that you two, would know so much about poo poo. LOL.

So thier you go Alwest now go buy a skimmer

kentrob11

10/15/2006, 09:09 AM

A quick chime in...While most of my skimmer building efforts have gone into NW skimmers, I will say that the best performing skimmer I have ever seen was a dual recirculating beckett made by Geo run with a 200gph blueline pump. that thing pulled out some serious mud but had the same problems other becketts seem to: major cleaning issues. I think that a recirculating beckett similarly sized with a bubble diffuser, coned riser and a wetneck would prove to be the best skimmer out there even if it did use 20% more electricity to run....Anyone want to build one?

bergzy

10/15/2006, 10:11 AM

pictures...we need pictures of direct nw and beckett use on the same system!

well, here is mine...

though the becket is huge and the nw is small, one can see the difference in skammate quality and quantity.

the one gallon jug is 6 hours on an aerofoamer 830 powered by an iwaki 55rlt (i have sinced upgraded to an iwaki 70rlt) and the little euroreef 5-2 with a sedra 3500 shows the nice dark skimmate amount after 48 hours of use.

http://i2.photobucket.com/albums/y38/bergzy/skimmatedifference.jpg

why run two (had two nw's on board but i fried one of the er's) different type of skimmers? for exactly the reason you see in the pic. different quality and quantity of skimmate.

alwest45

10/16/2006, 01:07 PM

Too much work. I think I'm caught up now on the thread. And it's still not all clear to me. A few questions.

>While most of my skimmer building efforts have gone into NW skimmers, I will say that the
>best performing skimmer I have ever seen was a dual recirculating beckett made by Geo run with
>a 200gph blueline pump.

kentrob11, the GEO was my #2 choice when I looked at the beckett skimmers. I ended up picking the Barr/Austin Oceans beckett skimmers (before I was drawn back to the new ER) because it was easy to clean - everything twists or snaps off and goes back together easily. But it looks to me like the GEO is a very high quality skimmer. The question I don't understand is this. Why do people say "I tried a beckett skimmer but it didn't work that well" and then when you ask them what kind it was they say either it was a no name skimmer or one they tried to build themselves. And then they compare it against a top of the line (usually) needlewheel skimmer! How is this a valid comparison? If I compare a no-name needlewheel against a GEO or Austin Oceans I wonder which one I'll end up thinking is the better kind of skimmer? For comparisons to be valid, I think you have to pick the best of breed and compare them. That's the approach I'm trying to take. There's a big difference between a well engineered needlewheel skimmer and a cheap no-name needlewheel skimmer. The same is true for becketts (maybe more true since the higher throughput probably requires better engineering to make it work up to full potential, i.e. it is a more difficult engineering problem).

On the subject of darker skimmate and pulling more out of the water, does anyone have any reference on the actual science behind this. When I used to ask this question before I always heard "Escobal covered this in his book". But it turns out this was just an assumption he made without (as far as I can tell) any research or other evidence. I understand the theory that if 10 seconds of dwell time get X amount of gunk out of your water and for 20 seconds you get X+Y out. For 100 seconds I suppose you get X+Y+Z and for 1000 seconds I suppose you could get even more (assuming even and adequate amounts of bubbles). But this all sounds like we are just guessing. It seems relatively easy to convert a beckett skimmer to a recirculating skimmer and put a very low flow pump driving the skimmer from your sump. No one seems to want to do this (MRC has recirculating beckett skimmers but they don't seem to be taking the world by storm). If slowing down the flow through the skimmer improves performance then why aren't the beckett guys all moving to recirc designs? Does anyone want to guess how much dwell time is optimal for any bubble? And what does the curve look like? Let's define the maximum organic extraction at 2 minutes, i.e. let's assume that diminished returns means we only want 2 minute dwell time because we aren't going to get much more waiting 3 minutes. Does anyone want to guess what the curve looks like? Where do you get 50% of the organics extracted? Where is the 75% point? What about the 90% point? Do you think this is a flat curve or more of a bell curve? Has anyone every seen any research that attempts to answer these questions? If not, who wants to guess?

I keep getting drawn back into the recirc skimmer argument. If Roland is right that the point of recirc skimmers is just to manage flow through the skimmer then why do we think they are better at getting out the stubborn molecules? The only thing that is going to get the organics out is a bubble. Why does a recirc skimmer have a longer bubble (not water) dwell time than a non-recirc skimmer? My old ER was the non-recirc variety and it could pull very dark and nasty stuff out of the water. You want your skimmer to produce lots of optimally sized bubbles. Too small and they won't rise. Too large and they rise too fast and don't have as much surface area as the smaller bubbles. Too much turbulence in the skimmer is bad since it will shorten the bubble life. I don't see anything in a recirc design that lengthens the bubble life. Once a bubble is created from the recirc pump it will either exit the skimmer, get sucked into the recirc input port and destroyed (and loose any organics it has collected on its surface), or burst through some other mechanism (turbulence, etc). The water hanging out in the bottom of the recirc skimmer body that does not have bubbles in it (where most of the recirc input comes from) does not really contribute to the extraction or stubborn organics. It is just sitting there waiting to be used for generating bubbles. It could just as well be sitting in the sump or in the tank. How does a recirc design contribute to increased organics extraction and if you think it does why don't the DD and beckett guys use recirc designs?

And please, does anyone have a pointer to any real research?

Al

sherm71tank

10/16/2006, 01:15 PM

I just finished converting a diy beckett over to recirc and it works great. The foam head is more stable and so far it looks like I can also run the water level higher than before. It is being fed with a maxi-jet 1200. I had to take it out to reattach the injector but should have it running again this afternoon.

alwest45

10/16/2006, 01:55 PM

<a href=showthread.php?s=&postid=8351881#post8351881 target=_blank>Originally posted</a> by sherm71tank
I just finished converting a diy beckett over to recirc and it works great. The foam head is more stable and so far it looks like I can also run the water level higher than before. It is being fed with a maxi-jet 1200. I had to take it out to reattach the injector but should have it running again this afternoon.

Ok, a data point. Why do you think it is better than before - why do you think the foam head is more stable? You are presumably injecting the same size and number of bubbles into your skimmer as before. So the big difference is that you are putting about 250 GPH through the skimmer instead of 800 GPH? What pump are you using to drive the beckett? Do you think it was excess turbulence before when you were trying to run the higher amount of water through the skimmer that made the foam head less stable? How did you engineer the water flow when you built the skimmer and did you take any steps to mitigate turbulence from the high flow rate? It seems to me that some of the lower end beckett skimmers out there do have a problem with higher flow and they have excess turbulence that requires you to lower the water height to keep things under control. On the other hand, my friend with the Barr/Austin Oceans skimmer runs a wet neck and doesn't have any burping or turbulence problems. I am wondering what is causing the benefit you are seeing and if my friend would see any benefit from converting to recirc? Let us know any other thoughts you have as to why you are seeing the benefits from the switch to recirc.

Al

sherm71tank

10/16/2006, 02:34 PM

When I was running it with the beckett feeding the skimmer and the air valve wide open it would very quickly fill with bubbles and over flow even with the water level set as low as possible. With the Maxi-Jet feeding it does not do this. I can actually raise the water level higher than I ran it before. Why? I do not know but it has to have something to do with throughput. I have a Dolphin DP-2000 pump and a Resun pump slightly smaller. I think the DP-2000 is a bit much for it so will use the Resun when I get it hooked back up. The beckett flows into a u-tube directed into the riser and an atrium grate for a diffuser which reduces the turbulance and I get almost no burping if any. I put this skimmer together from parts of several other skimmers. There is no step to the collection cup it is tapered. I'll try to get some pics of it later tonight.

kentrob11

10/16/2006, 02:38 PM

I think that a big 4-5' x 12" diameter reaction chamber dual recirculating beckett skimmer with a good pump, wetneck and a bubble diffuser would be really tough to beat by any of the top needlewheel skimmers. JMO....

Roland Jacques

10/16/2006, 03:09 PM

<a href=showthread.php?s=&postid=8351812#post8351812 target=_blank>Originally posted</a> by alwest45

I keep getting drawn back into the recirc skimmer argument. If Roland is right that the point of recirc skimmers is just to manage flow through the skimmer then why do we think they are better at getting out the stubborn molecules? The only thing that is going to get the organics out is a bubble. Why does a recirc skimmer have a longer bubble (not water) dwell time than a non-recirc skimmer? Al

I like your questions. you put a lot of thought in them. I'm glad you pointed out you are talking about "bubble" dwell time".

To clarify my words were, recirc biggest advantage is MAINLY from controlled flow. not "just" "mainly".
Increased in air from recurculating a skimmer can be as much as 25% higher or more on some taller models skimmers. Form the lower back pressure...

Roland Jacques

10/16/2006, 03:39 PM

Ken, i never really gave much thought to the recirc beckett. it sound like somthing worth looking at. I know H2o ENG makes them and MRC make them too. i going to look closer at those. got to go by MRC next week any way. what model did you look at?

alwest45

10/16/2006, 03:41 PM

Roland, I hear you. But in a typical? sump & needlewheel skimmer setup the skimmer is fed by a feed pump. Those Sedras won't suck enough water from the sump to get the 1-1.5X turnover that Euroreef recommends (as 1 example). If you are feeding your needlewheel skimmer with a feed pump is there any difference in head between the circ and recirc versions? If there is, it seems like it would be a lot less than 25%?

Al

kentrob11

10/16/2006, 04:16 PM

The recirculating beckett I saw pulled out an amazing amount of the muddiest crap I have ever seen out of a skimmer. It was run with a really high wattage pump though. The problem with it, besides the high wattage pump, was that it head to be cleaned ALL the frikin time!
With a good wetneck and a bubble diffuser to dissipate some of the turbulence, I think it would be the best performing skimmer out there. someone recommended a sequence pump at 175 watts for a dual beckett skimmer and I think that with that setup, we would have a real winner......

sherm71tank

10/16/2006, 04:18 PM

I am currently running the RPS 2000 skimmer with an OR2700 as the feed pump. It works pretty well but nothing compared to the beckett in regular or recirc configuration. Granted though the beckett does use a bigger pump. Here is a pic of the front.

http://reefcentral.com/gallery/data/500/43852IM001321.JPG

After I get it running I'll post a pic of it after 10 minutes.

kentrob11

10/16/2006, 04:24 PM

Here's a pic of the skimmer I was talking about....

http://reefcentral.com/gallery/data/500/2963daves_skimmer.JPG

sherm71tank

10/16/2006, 04:27 PM

Thats a monster!

kentrob11

10/16/2006, 04:44 PM

Tell me about it. I swear the last time I saw it up and running it looked like the entire Vienna boys choir took turns sitting on it after a long night of Taco Bell and EX-LAX milkshakes.... One of these days I'm going to build one the way I think it should be built just for the heck of it....

sherm71tank

10/16/2006, 05:19 PM

I have two shots. One is the Dwyer flowmeter showing almost 50scfh. The pump is 125 watts. Not bad?

http://reefcentral.com/gallery/data/500/43852IM001322.JPG

http://reefcentral.com/gallery/data/500/43852IM001323.JPG

The diffusor makes a big difference, at least on a beckett this size.

alwest45

10/16/2006, 05:32 PM

<a href=showthread.php?s=&postid=8353552#post8353552 target=_blank>Originally posted</a> by sherm71tank
I have two shots. One is the Dwyer flowmeter showing almost 50scfh. The pump is 125 watts. Not bad?

What pump are you talking about that's 125 watts? Is the 125 watt pump driving 1 or 2 becketts and is that the pump that's producing the 50 scfh?

sherm71tank

10/16/2006, 05:35 PM

It is driving one beckett in recirc. It is a Resun pump a little more than a Dolphin DP-1200 in flow rate. About 850 gph @ 12' head height. Yes it is the one producing 50 scfh. Using the maxi 1200 for feed pump.

hahnmeister

10/16/2006, 08:25 PM

sherm71tank, 50scfh for 125watts is well...

Its all relative to the height of the skimmer too... A 6' tall skimmer may not get as much SCFH as a 3' skimmer, but it might pull out more due to contact time.

But just to give you an idea... the ATI bubblemasters do 80-90SCFH for a mere 60 watts. That might be an exteme enabled in part by how short the ATIs are, along with many BubbleKings, but thats still about 4x the SCFH/watt that you are getting. A Dart NW can do about 80-100scfh on its own on a 5' tall body, for what... 120watts about?

sherm71tank

10/16/2006, 08:38 PM

Don't have any experience with the ATI's but they do look promising. I don't know where to get a Dart NW. The power curves I've seen on the Dart put it anywhere between 110 and 160 watts depending on feet of pressure.

JC VT

10/16/2006, 09:58 PM

On the subject of darker skimmate and pulling more out of the water, does anyone have any reference on the actual science behind this.

Wet skimming, intuitively, pulls more out. The nasty stuff is locked up in a bacterium, food mass, detritus, etc.

Here's a quote by Randy Holmes Farley:

For this reason, I believe that the greatest skimming will come from removing a relatively wet foam, rather than waiting for this same wet foam to drain prior to removal. The only difference between a wet foam, and one that has drained more to form a dry foam, is that additional water, and some organics, have drained away. I believe that this important point is often neglected.

I understand the theory that if 10 seconds of dwell time get X amount of gunk out of your water and for 20 seconds you get X+Y out. For 100 seconds I suppose you get X+Y+Z and for 1000 seconds I suppose you could get even more (assuming even and adequate amounts of bubbles).

I think there is marginal utility in too much dwell (1000 seconds). A clean bubble will have more ability to take out 'stuff' than a dirty bubble. By extension, a clean bubble will be able to take out "stubborn" molecules better, also.

alwest45

10/16/2006, 11:00 PM

<a href=showthread.php?s=&postid=8355446#post8355446 target=_blank>Originally posted</a> by JC VT
Wet skimming, intuitively, pulls more out. The nasty stuff is locked up in a bacterium, food mass, detritus, etc.

Here's a quote by Randy Holmes Farley:

For this reason, I believe that the greatest skimming will come from removing a relatively wet foam, rather than waiting for this same wet foam to drain prior to removal. The only difference between a wet foam, and one that has drained more to form a dry foam, is that additional water, and some organics, have drained away. I believe that this important point is often neglected.

I think there is marginal utility in too much dwell (1000 seconds). A clean bubble will have more ability to take out 'stuff' than a dirty bubble. By extension, a clean bubble will be able to take out "stubborn" molecules better, also.

Yes, I saw the article by Randy Holmes-Farley and I thought it was very useful. For those that haven't had a chance to read it (it's in the August 2006 issue of Reefkeeping) you should. Randy's opinion is an interesting datapoint and when you think through the physics involved it does make sense.

I didn't really mean we should shoot for 1000 seconds of dwell time. I'm just trying to understand if anyone really knows about getting these "stubborrn" molecules out of the water or not. I do keep hearing 90-120 seconds as a recommendation for dwell time but there does not seem to be any real evidence or research to back that up. And even if 2 minutes is the right number, does anyone understand what percentage you get out if your dwell time is less than 2 minutes?

When we say dwell time does everyone agree that it's bubble dwell time, not water dwell time? How do you calculate bubble dwell time? It's some function of bubble size, countercurrent flow, and turbulence I presume?

Al

JC VT

10/16/2006, 11:43 PM

I didn't really mean we should shoot for 1000 seconds of dwell time. I'm just trying to understand if anyone really knows about getting these "stubborrn" molecules out of the water or not.

I didn't either. Theoretically a clean bubble with low turbulence would do the trick on a "stubborn" molecule.

On the other hand, no one in this thread has identified what a "stubborn" molecule is, if it exists, what it might be, why current skimmers would not take it out as well, why a needlewheel would get it out better than a beckett, and whether or not anything in your reef tank cares if its not skimmed out immediately.

Roland Jacques

10/17/2006, 05:49 AM

<a href=showthread.php?s=&postid=8355810#post8355810 target=_blank>Originally posted</a> by alwest45

When we say dwell time does everyone agree that it's bubble dwell time, not water dwell time?
Al [/B]

Oh my goodness your right. I've been referring to as "dwell time" being water time only, I see where some may be using it as bubble time in some conversations. No wonder we have hard time communicating, that and my spelling. It seems that most people use it as water time.

I will in the future refer to them as "water dwell" and "air dwell" sorry about the confusion, good catch, thanks.

now that you point that out, I don't no enough words to describe the aspects of skimming. Anybody have a link to skimmers words & definition

alwest45

10/17/2006, 09:38 AM

Roland, do you agree that water dwell time has nothing to do with removing organics? This assumes of course that it takes a bubble to remove organics. Is there any confusion on this point?

sherm71tank

10/17/2006, 10:18 AM

Bubble contact time is what it's all about. But if you can make the same water make multple passes through a column of bubbles within the skimmer making the water cleaner with each pass then doesn't that make the harder to extract proteins more likely to be removed? If you take a skimmer can only be x% efficient then multple passes with the same water before being recontaminated seems like a good thing.

alwest45

10/17/2006, 11:16 AM

<a href=showthread.php?s=&postid=8357646#post8357646 target=_blank>Originally posted</a> by sherm71tank
Bubble contact time is what it's all about. But if you can make the same water make multple passes through a column of bubbles within the skimmer making the water cleaner with each pass then doesn't that make the harder to extract proteins more likely to be removed? If you take a skimmer can only be x% efficient then multple passes with the same water before being recontaminated seems like a good thing.

I'm not sure this is correct. Rather than concentrate on trying to scrub the last bad stuff from your water in the skimmer and letting the easy to clean organics stay in your tank, it seems like you should get all the low hanging fruit first since it is quicker and easier. When you've gotten all the easy to clean molecules out (which I'm assuming is the majority of the organics that a skimmer can remove) then you can try to get more stubborn molecules (whatever they are) out. This is a little like cleaning the glass (acrylic) on the front of my tank. I don't want to focus just on cleaning one small spot to perfection - I want to clean the entire front glass first. Then when that's done, I can focus my attention on cleaning those spots of stubborn coralline algae that didn't come off in the first few passes.

Again, can anyone point to some data on what these "stubborn" molecules are?

Roland Jacques

10/17/2006, 01:28 PM

<a href=showthread.php?s=&postid=8357501#post8357501 target=_blank>Originally posted</a> by alwest45
Roland, do you agree that water dwell time has nothing to do with removing organics? This assumes of course that it takes a bubble to remove organics. Is there any confusion on this point?

No I don't agree,

When most people talk about dwell time I they are talking about water. I think we assume that air bubbles are a given. So with that assumption water dwell does have a lot to do with removing organic. You question as to how much of a factor is it is a valid one. it can be tested easaly

Typically we cant control bubble dwell. This is a given, for a particular skimmer design. For the most part, we cant make a bubble speed up or slow down it's time in a skimmer. We just want the maximum air dwell and air volume while maintaining the smallest possible bubble as possible( with the bubbles still being able to rise to the foam). so i believe most conversations about dwell is talking about water time interacting with bubbles IMO. "Contact time" may be a better name but even that is a little bit misleading and not 100% accurate. Water dwell is what most of this conversation has been about. Hits or bombardments may be better words I need to look them up but most of my book are in storage.

<a href=showthread.php?s=&postid=8352935#post8352935 target=_blank>Originally posted</a> by alwest45
Roland, I hear you. But in a typical? sump & needlewheel skimmer setup the skimmer is fed by a feed pump. Those Sedras won't suck enough water from the sump to get the 1-1.5X turnover that Euroreef recommends (as 1 example). If you are feeding your needlewheel skimmer with a feed pump is there any difference in head between the circ and recirc versions? If there is, it seems like it would be a lot less than 25%?

Al

Al,
I missed this one
The answer to this is yes. The NW200 in sump skimmer (no feed pump) i tested in 4" of water it pulled 8 Scfh of air when i raised the water level in the sump up to 10" it pulled 11 scfh so head pressure does reduce the amount of air recirc Vs non recirc. In this real example test the results were 35% incease in air.

And the other point here is those sedra well suck to much water. The in sump skimmer pulls to much new water in it. The insump skimmer pump move 300-600 gph on a skimmer rated at 100 gallons. The recirc allows you to slow that down to 150-200 for you 1.5 - 2 Xs this is the main reason people want recircs, to slow down the flow.

This leads to a simple test about stubborn proteins question. you can simply compare identical nw recirc skimmers with different flow rates. See which pulls more and or stankier poop. I would imagine this test has been done many times. But ive never tested that.

Fudge

10/17/2006, 06:02 PM

Hello all,

My eyes are buggin from this, very informative thread...unfortunatly im still a bit lost when it comes to the numbers involved.

Maybe someone could help me with the math here ..

I am Currently running a Quad-beckett, a 5800-1100 series sequence for recirc, an 8" body 40" tall with a diffuser plate for a little less turbulence.
It is fed with about 600 gph tank water.

I am interested always in ways to make this power hungry tank a little more economical...but dont want to downgrade at all.

I would like to build a 20" diam 36" tall NW dart...or dual dart ?
This is where im getting lost.

Does that mean i could estimate i see about an average of 180 total scfh now... so 2 darts is the only way to get those numbers? Even then, the only improvment would be the 20 scfh difference the 2 darts are, at an average of approximatly 200 scfh ?
It would seem ive just lost the power consumption improvement.
So im left with the differences in the tube diam to increase contact time,or to change water dwell times to make it a worthwhile project ?

Im just baffled trying to figure out water and air dwell time from one to the other.

So given the chamber sizes above, how would that skimmer be an improvement over my existing one....or would that even be one at all ?
What would be your guess as to the way to make a better improvement ?

Thank you for any help anyone who want to take a stab at an answer.
i apologize if this derails the thread in any way.
Marc.

sherm71tank

10/17/2006, 06:19 PM

If you are going to use a large air pump like an Alita then why not just make a large cc skimmer? I've seen some really nice ones around here and they work great if you have room for one.

Roland Jacques

10/17/2006, 06:46 PM

here is a link to a skimmer build using a dart pump. A dart NW can get about 170 scfh with a air pump.
hes built a nice tinymight skimmer
He trying a new wheel this time but i dont no if we understand the mesh wheel good enough yet to take full advantage of its ability to produse bubbles. i think the tiny might may be a better choise than a dart for the lowest watts mesh wheel bubble pump, just a hunch.

http://reefcentral.com/forums/showthread.php?s=&threadid=950690&perpage=25&pagenumber=2

hahnmeister

10/17/2006, 10:48 PM

Ahhh, the old argument of dwell time vs. contact time. You know, of all the arguments and discussions I have had here over the years, I have never had a scientific or informed response to the question of 'can contact time mean dwell time?', as in, does the ideal of a 120second dwell time mean the time it takes one bubble to make it to the top, or the time the water spends in the skimmer. I would love it if someone would finally respond to this.

From all of the research I have done, I have gotten this. They are not the same, but, with enough exposure/contact time, the dwell time can be made up for. So there are some of these harder to attract proteins that need a longer dwell time to get taken out. Ok. I get it. And if the turbulence is too high, or the bubble gets to the top and the protein isnt exactly ready... well, what does happen to it?

A 120minute dwell time suggests that the bubble and protein have been together for some time... and since the bubble doesnt stay still, the protein must travel with it. I cant find any other way to explain it, or other way that these proteins would arrive there. Well, on a larger skimmer, or at least one with a decent foam head... what happens to these proteins if they reach the top of the skimmer and the end of the bubble's path? Well... unless they shake off before they reach the foam head for some reason, they would in effect stay in the foam head, right?

I mean, sooner or later, the multiple passes of a recirculating skimmer would mean that the harder to skim proteins will make it to the top portions of the skimmer. This explains the performance advantage of recirculating skimmers, even if you compare one with the same size pump/air throughput and skimmer body. This also explains why a beckett tower can churn out such vile filth. Becketts are the antithesis of a recirculating needlewheel or countercurrent skimmer. They blow tons of air bubbles down downdraft looking turbulent towers where the violence would suggest that there is little to no dwell time going on. Its the exact opposite of a Bubble King... yet it still performs very well. The bubbles then get deflected from their downward path in the 'black box' at the bottom, and the bubbles shoot up into the riser area where the foam path is pretty short. The water makes a quick pass in the black box and is out of the skimmer. The foam head starts pretty low in these guys, and it very tall. The contact time and dwell time are little to none... but they have tons of foam head where proteins can get trapped and get the rest of that 120second exposure in dwell time. Not in the water, but in the head. In this respect, the BK and the Barr Beckett are very much alike. BKs arent very tall skimmers mind you, and that bubble plate doesnt exactly make for a longer bubble path than a mixing pump with a downward facing output... but it does make for a stable foam head... a thick foam head.

I think that with enough passes and a nice foam head, a recirculating skimmer that is only 24" tall can extract those 120second proteins. Dwell time is a great goal, but if you dont have a 6' skimmer, then a muti-pass (recirculating downdraft) and a thick foam head can make up for it.

alwest45

10/17/2006, 11:26 PM

<a href=showthread.php?s=&postid=8358741#post8358741 target=_blank>Originally posted</a> by Roland Jacques
No I don't agree,

When most people talk about dwell time I they are talking about water. I think we assume that air bubbles are a given. So with that assumption water dwell does have a lot to do with removing organic. You question as to how much of a factor is it is a valid one. it can be tested easaly

Typically we cant control bubble dwell. This is a given, for a particular skimmer design. For the most part, we cant make a bubble speed up or slow down it's time in a skimmer. We just want the maximum air dwell and air volume while maintaining the smallest possible bubble as possible( with the bubbles still being able to rise to the foam). so i believe most conversations about dwell is talking about water time interacting with bubbles IMO. "Contact time" may be a better name but even that is a little bit misleading and not 100% accurate. Water dwell is what most of this conversation has been about. Hits or bombardments may be better words I need to look them up but most of my book are in storage.

....

I do think we have a difference of opinion here. I understand the difference between bubble dwell time and water dwell time but it seems to me that the one that really counts is the bubble dwell time. How does it matter if the water in the skimmer is being recirculated back through the skimmer body or recirculated back through the sump and then back through the skimmer body (or even back through the tank, then the sump, and then the skimmer body)? It's just water being pumped to some other location before it gets a chance to be exposed to bubbles again and maybe give up some of the organic molecules it is carrying to the air/water interface. Why does the amount of time that water spends in a skimmer body matter? Why can't you get different water directly from the tank (it's probably dirtier water so it will likely give up it's organic molecules easier) and use that instead of recirculating the same water over and over inside the skimmer body?

Roland, I totally get the flow control issue with recirc skimmers. But it seems that many other people believe that recirculating water inside the skimmer body will make for a better reef tank and that their water will somehow be "cleaner". I don't see how the overall reef tank water quality improves by recirculating the skimmer body water.

Isn't the real key here how much bubble dwell time you can get? Because it's the bubble that will do the work. This is leading me to think of a point Zephrant mentioned some number of posts back in this thread about contact distance. Isn't that going to be a very important factor, i.e. how many inches the bubble has to travel from when it is generated until it escapes out the neck of the skimmer? Of course you have to look at other factors like how fast the bubbles travel over this distance and whether turbulence causes bubbles to be destroyed before they can reach the neck but I am thinking that the bubble contact distance and bubble dwell time are much more important that water dwell time inside the skimmer body.

(Please pardon the poor artwork skills)

Why is the first picture any different from the second?

http://reefcentral.com/gallery/data/500/133419skimmerpic1.gif
http://reefcentral.com/gallery/data/500/133419skimmerpic3.gif

(pictures fixed)

alwest45

10/17/2006, 11:41 PM

<a href=showthread.php?s=&postid=8362458#post8362458 target=_blank>Originally posted</a> by hahnmeister
Ahhh, the old argument of dwell time vs. contact time. You know, of all the arguments and discussions I have had here over the years, I have never had a scientific or informed response to the question of 'can contact time mean dwell time?', as in, does the ideal of a 120second dwell time mean the time it takes one bubble to make it to the top, or the time the water spends in the skimmer. I would love it if someone would finally respond to this.

.....

Hahn, I think I get everything you said except I still don't understand why water circulating inside the skimmer body is somehow better than new water from the tank. Unless of course you need to first strip out the "easy" molecules so they don't crowd out the "stubborn" molecules and thereby give them a better chance to connect to the bubble? I agree that I don't see how the bubble can attract those stubborn molecules unless it can weakly attract them much earlier and then use the rest of the 90-120 seconds (or whatever it takes) to build a stronger bond that will allow it to keep the "stubborn" molecule all the way up the neck. But rather than give all the extra "capacity" away trying to get the "stubborn" molecules, wouldn't it be better to first go for the easy to attract molecules? That way you are removing the largest amount of gunk first and when you get the easy to clean molecules out of the way then your bubbles can work on sttracting the stubborn molecules.

Also, do you think that a well engineered, tall recirculating Beckett skimmer would perhaps be the best solution? Any idea why the Beckett skimmer guys don't seem to be jumping on the recirc bandwagon, at least not to the extent that the NW guys are?

hahnmeister

10/18/2006, 12:26 AM

I would say that the proof is in the puddin... recircs, even those that use the same size pump and body as a single-pass, get more out.

As for the contact time making up for dwell time, I covered it in my last post pretty well... The proteins, even if they are more stubborn, are going to get taken upwards inside the skimmer anyways due to the updraft. I agree that a bubble dwell time is the ideal, but it can be made up for with good head and recirculating... at least thats what Im suggesting.

Or, perhaps its not even the dwell time, but other chemistry at work. Its no secret that higher ORP results in better skimming and waste handling. And even without an ozone generator, a skimmer does buffer the ORP. Perhaps the lower throughput of the recirculating skimmer allows it to reach a higher internal ORP, therefore allowing it to achieve a much higher skimming.

I have heard reports from people that the super saturation that ETSS and other downdraft skimmers provide gave their tanks a much higher ORP than running a needlewheel. It was unexpected when someone told me that, but it does make sense.

Perhaps its the ORP...

And yes, watt for watt, Becketts start to make more sense when you get into systems that are over 300g. Needlewheels have the advantage of lower watts in smaller sizes, but as you get taller, needlewheels tend to choke out on the head-pressure, and you start to see more pumps... so that single 50-60 watt mixing pump just got multiplied by 4 or 5... thats 400+ watts! now Becketts dont look so bad.

But there are the exceptions. ATI has been able to pull 100scfh with an eheim 1262 NW, and Bubblekings do even more with less wattage. I would say that a large Dart Needlewheel would also be a contender... able to work on 5' tall skimmers with ease and generate scfh numbers that would make a beckett skimmer cry.

Roland Jacques

10/18/2006, 07:03 AM

I think you need to understand this for the rest to make sence. The Bubble dwell time is no different in a recirc NW skimmer than a insump NW skimmer.

Thier may be slight vareiances maybe 2%-3%. More than not in the bubble dwell would be in favor of the in sump model. (in you tipical skimmer) not the recirc. So rule that out as contributing to the recircs better performace.

Pyrrhus

10/18/2006, 09:31 AM

With a recirc skimmer you can indeed increase the bubble dwell time. All you need to do is restrict the air intake on the recirc pump. Less air flow=more water flow, which leads to greater entrainment of the bubbles in the water column leading to a longer bubble dwell time.

hahnmeister

10/18/2006, 11:44 AM

<a href=showthread.php?s=&postid=8363465#post8363465 target=_blank>Originally posted</a> by Roland Jacques
I think you need to understand this for the rest to make sence. The Bubble dwell time is no different in a recirc NW skimmer than a insump NW skimmer.

Thier may be slight vareiances maybe 2%-3%. More than not in the bubble dwell would be in favor of the in sump model. (in you tipical skimmer) not the recirc. So rule that out as contributing to the recircs better performace.

Right, the dwell time, as in the time it takes for a single bubble to rise from the bottom to the top, isnt changed much (although a recirc is a downdraft, so technically, the bubble does take longer to rise), the overall contact time is. The throughput on a recirc skimmer is often 1/4 or less what the throughput might be of a single-pass skimmer... so thats a 4x contact time. Thats what Im saying... that perhaps contact time can make up for less dwell time... or that perhaps a really thick foam head at the top can extend the dwell time, since the bubbles can stay there in suspension for a much longer time than they were on the way there.

And thats what I wonder... did Escobal and all these other skimmer people define what dwell time is in relation to contact time?

alwest45

10/18/2006, 03:33 PM

<a href=showthread.php?s=&postid=8365178#post8365178 target=_blank>Originally posted</a> by hahnmeister
Right, the dwell time, as in the time it takes for a single bubble to rise from the bottom to the top, isnt changed much (although a recirc is a downdraft, so technically, the bubble does take longer to rise), the overall contact time is. The throughput on a recirc skimmer is often 1/4 or less what the throughput might be of a single-pass skimmer... so thats a 4x contact time. Thats what Im saying... that perhaps contact time can make up for less dwell time... or that perhaps a really thick foam head at the top can extend the dwell time, since the bubbles can stay there in suspension for a much longer time than they were on the way there.

And thats what I wonder... did Escobal and all these other skimmer people define what dwell time is in relation to contact time?

Hahn, when you say a recirc skimmer has maybe 4x the contact time of a non-recirc skimmer (same body/design/size) are you talking about (A) bubble contact time or (B) water contact time. If A, then I don't see it. Other than the small percentage gain you get from the downdraft action of the recirc skimmer it seems the contact time is the same since the bubble still has the same distance to rise. If you mean B, how does it matter whether the water in the skimmer body is mostly "the same" water that was there 30 seconds ago or if it has been swapped out with "new" water from the tank?

Btw, I like your foam theory. I've not heard it before but it does explain a lot of things that were hard to understand. But it does seem to imply that it is relatively easy for a molecule (even one of those elusive "stubborn" molecules) to latch on to a bubble so that it can jouney up to the foam head - it's just that the "stubborn" molecules need more time to get attached enough so they don't detach before the foam exits the skimmer. If correct, isn't this a fairly radical new theory on skimming?

Roland, when you say "The Bubble dwell time is no different in a recirc NW skimmer than a insump NW skimmer" I understand your point. However, it seems to me that most of the other folks talking about needlewheel skimmers don't seem to agree. It seems like they attribute the superior performance of recirc needlewheels (over non-recirc needlewheels) to longer bubble dwell time "since the water recirculates inside the skimmer body". But as you point out, that doesn't seem to be true. But if you are correct (and I believe you), then how to account for superior performance of recirc NW skimmers other than re-exposing partially skimmed water to another wave of bubbles somehow works better than exposing unskimmed (i.e. dirtier) water to the same number of bubbles. How can that be. Or am I somehow missing the explaination for why recirc NW skimmers seem to work better than non-recirc NWs?

Could it be that recirc needlewheel skimmers are the latest versions from the skimmer vendors and as the latest versions they have other engineering tweaks intended to improve their performance which collectively are what's responsible for the perceived improvement of recirc NWs vs. the old-style NWs?

Hey Fudge, what vendor makes your quad-beckett skimmer? What pumps are driving it? Are you getting 180 scfh through it now? It sounds like a good setup for your large SPS tank. Why do you want to change?

Al

alwest45

10/18/2006, 03:41 PM

<a href=showthread.php?s=&postid=8364278#post8364278 target=_blank>Originally posted</a> by pyrrhus
With a recirc skimmer you can indeed increase the bubble dwell time. All you need to do is restrict the air intake on the recirc pump. Less air flow=more water flow, which leads to greater entrainment of the bubbles in the water column leading to a longer bubble dwell time.

Boy, this seems counterintuitive to me but maybe I misunderstand. Are you saying that decreasing the scfh of the skimmer would increase the bubble dwell time because you would have a stronger countercurrent downflow in the skimmer body due to the larger amount of water (less air means more water in this zero sum game)? But don't you want to increase the aggregrate bubble dwell time and to do that you need more bubbles. It may not matter what a single bubble does or what it's dwell time is. Isn't what really matters some kind of product of the average bubble dwell time times the number of bubbles in the skimmer (minus those that are destroyed)? To improve this it seems like you need more air going through the skimmer. Isn't one of the major goals of skimmer design to improve (increase) the scfh while not increasing the bubble size or turbulence? Won't that approach lead to better skimming?

Roland Jacques

10/18/2006, 03:51 PM

Al, spent some time with Andy & Tim today over at My Reef Creations. They where setting up thier new recirc skimmer on their reef in the lobby. It is a recirc beckett Mr 3 they said

" it easyly out perform the MR-5 . it is because you can reduce the flow through the skimmer by half". FWIW

It mean nothing to me but FWIW thier recircs are doing great in sales.

Roland Jacques

10/18/2006, 04:32 PM

Zoom

10/18/2006, 04:44 PM

Ok what about my skimmer .
the skimmer is .
1) Swirl design.
2)Counter current
3) Recirc PW with two Eheim pumps
4) 40" tall by 10" diameter.

You think i can do better?

alwest45

10/18/2006, 06:32 PM

Zoom/Steve, I've been on a quest for the "best" skimmer I can find for my new 240-300 gallon reef tank (mainly SPS with some fish and a few clams). Here's what I came up with:

1) Austin Oceans/Barr Aquatics Foaminator MAX 5000 (4' beckett skimmer, field upgradable to 2 becketts with a Sequence Tarpon pump (quiet and relatively low watts - for a beckett). This looks to me to be the best beckett skimmer out there and was my #1 pick. Does 45 scfh on a single beckett, 90 scfh if I upgrade to dual becketts (I like the easy doubling of airflow when my tank gets a little more crowded and needs a boost on performance). Very high quality construction and materials. Plus I couldn't find a single customer that had anything but praise for these skimmers. This was my #1 choice.

2) Euroreef RC250 with 2 Gen-X 4100 pumps with the new Euroreef impellor (supposed to do 76 scfh). A very solid and quality product plus only 30" tall so I could fit it under my stand if needed. Quiet and reliable. The rumor I hear is the ER is also improving their customer service so I've currently had this model as my number 1 pick. A little pricy but I'm looking for the best.

3) Deltec AP902 with 2 Eheim 1260 needlewheel pumps (56 scfh). A quality German skimmer and most of the people that have them love them - however, you will hear some grumbling if you listen closely. Quiet and reliable with top notch construction and materials. But you know that because this is what you have now!

4) H&S A200-2s1260 with 2 Eheim 1260 needlewheel pumps (56+? scfh). Another quality German skimmer that is similar to the Deltec but cheaper. Eheim pumps are very quiet and reliable. Not too tall either. I thought that ER customer service might be easier since they are in the US (I can hear those people that hate ER customer service groaning now). It won out over Deltec in my mind but could beat the ER or Austin Oceans skimmers on cost. Even though it is cheaper than Deltec it is a little dear too.

4) BubbleKing 250 External. A real bragging rights skimmer that performs well (53 scfh), is very quiet, and low on power usage. Top quality construction and materials too plus German cachet. And to top it off all your friends will be impressed you could talk you wife into spending this much for a skimmer - price tag was too much for me particularly since I could get better performing skimmers (AO & ER) for less. However, if you are looking for a conversation piece or a divorce.....

I think the Austin Oceans or Euroreef will deliver better performance than you are seeing with your Deltec. I really like the 2X performance kicker when you need it option on the Austin Oceans beckett skimmer (where else can you get another 45 scfh for $129 plus another pump?). But I'm currently sticking with the Euro-reef RC250 for it's out of the box simplicity and impressive 76 scfh performance.

That's my take on the "best performance" (not best value or lowest power usage or even most efficient power usage) skimmer today if you have a "starting to get large reef tank" (i.e. 200+ gallons). If you are under 100 gallons, then it's a whole new ballgame and I would probably still go with ER for their "short but a lot of air" (new impellor) designs. For 300 or larger (either now or a planned upgrade) I would definitely go with the Austin Oceans (Barr Aquatics) dual beckett skimmer.

Al

sjm817

10/18/2006, 07:08 PM

AFAIK, the ER RC250 has a single SP5. The RC500 has 2xSP4, but the newest ones have 2 x Eheim 1262 pumps. Performance of the SP4 and Eheim are similar, but the Eheim is quieter.

hahnmeister

10/18/2006, 07:49 PM

alwest45,
In my writing so far above, I termed dwell time as the time it takes for a bubble to rise from bottom to top, and contact time as the time the water spends inside the skimmer. So 'B', according to your question. The amount of time that the water spends in the skimmer matters somehow... the proof is in the puddin'... but there are theories.
1.Perhaps the dwell time can be interchanged with contact time (as in, they are the same)... the time it takes for one protein to get attracted to a bubble might be cumulative (the protein doesnt need to have 120seconds with one bubble but could be many)...in which case this is true. Otherwise, if they are not the same, it stilll suggests that the harder to capture proteins are still being drawn upwards in the skimmer, even if they are not extracted right away. In which case, they would eventually end up in the foam head where the remainder of the ideal 120second dwell time can be achieved. More throughput would mean there is a higher turnover, meaning less time with each protein.
2. Perhaps dwell time can not be interchanged 1:1 with contact time, but perhaps more contact can make up for dwell time... like a 4:1 ratio or something. So the lower throughput of a recirc skimmer would mean more contact time.
3. The lower throughput could raise the ORP more... causing better skimming. A higher throughput would mean the incoming fresh tank water would lower the ORP, and it would take that much more air to raise the ORP.
4. The countercurrent nature of recirc skimmers means fresh water enters at the top, and has to travel through the whole height of the skimmer before it exits the bottom. Single pass skimmers have the water and air enter near the bottom, just inches from the outlet. The water can travel 6" and exit, not like a recirc skimmer.

As for the theory, so far, the attraction of proteins that chemists describe doesnt take much of the physical account of how the two travel together. What, the bubble is moving, so does a protein just hang around the top waiting for the bubble to reach the right age before latching on and going out the top?

From what I remember, proteins naturally build up in the top layers of the aquarium water... the proteins and oils are less dense than saltwater. So all in all, it would be reasonable to suggest that a protein could be dragged up to the top, knocked off the bubble, but still remain in the top areas of the skimmer. The proteins have to travel with the bubble to some extent... dont they? I mean, the interaction of the air and bubbles has been suggested to be a mutually dependent variable, neither the air nor the water's time is independent... its the interaction between the two.

alwest45

10/18/2006, 08:19 PM

<a href=showthread.php?s=&postid=8368223#post8368223 target=_blank>Originally posted</a> by sjm817
AFAIK, the ER RC250 has a single SP5. The RC500 has 2xSP4, but the newest ones have 2 x Eheim 1262 pumps. Performance of the SP4 and Eheim are similar, but the Eheim is quieter.

Arghh. Haste makes waste. Replace everytime I said RC250 with RC500. That's my current selection for my new tank setup, not the RC250. The performance numbers are for the RC500 with the new impellor.

The RC500 on the ER website still says 2xSP4. I would prefer Eheims though.

I originally was comparing the RC750 with the others on my list but when looking at the numbers it seemed that the RC500 would be a better match for comparison. Apparently when I was making my list today I stepped the ER down another notch....

sherm71tank

10/18/2006, 08:30 PM

All this NW vs. Beckett talk inspired me. I switched out the 1/4" valve and air line I was using on my beckett with 3/8" and now I'm getting about 75 SCFH. So there! (Don't rain on my DIY parade to much guys!)

alwest45

10/18/2006, 08:48 PM

Hahn, thanks for the more detailed explaination. I'm still struggling with the contact time, i.e. the time the water spends in the skimmer, and I have difficulty understanding the theory behind why this is good. Of your hypothesis #1 (dwell time and contact time may be 1:1 interchangeable), wouldn't this be true for all skimmers and not just recirc skimmers. In fact, wouldn't this be also true for beckett skimmers?

For #2, I understand the concept but don't see any reasonable theory as to why having the same partially skimmed water in the skimmer body makes for better skimming (other than perhaps the below)

For #3, you theorize that the ORP inside the skimmer body is driven up higher than the ORP in the reef tank itself and that higher ORP allows the proteins to more readily attach to bubbles or some other mechanism that makes for better skimming. I understand this point. Do you know of any evidence that supports this? This seems somewhat related to using ozone which will further reduce some organics and some people like to use ozone injected into the skimmer. As I understand it, Randy Holmes-Farley has weighed in on this topic and is of the opinion that ozone reduces the effectiveness of skimmers and that he recommends that if ozone is used it be used in small amounts. I understand that ozone uses a different process to raise ORP than skimming itself but given this data point with ozone do you think that the artificial raising of ORP inside the skimmer body actually improves the ability of targeted molecules to latch onto bubbles and be removed? (so far this is the only theory that I've seen that actually could explain why recirc water skims better so if this isn't true I'm back to square one).

FOr #4, what you say is certainly true. However, if we look beyond NW skimmers to becketts or DD skimmers, then you can see some longer bubble paths. And while some of those bubbles will certainly travel faster than a NW with a slow feed pump, some portion of the beckett bubbles will lose their momentum and travel at a normal bubble rise rate to the skimmer neck. One of the data points I noticed for the Austin Oceans/Barr skimmer was that the bubble path was over 100 inches. If this is important, then the Euro-reef RC500 that I'm planning for, which is only 30 inches in total height so the bubble travel distance is something closer to 24 inches, would be at a disadvantage. But this point I think does not explain the value of reskimming previously skimmed water - it just points out that if there is such a difference then recirc skimmers have an advantage. It's the theory behind the advantage I'm still searching for.

Btw, thanks for your time and efforts to convey your thinking on this - it has been very useful for me.

Al

alwest45

10/18/2006, 08:49 PM

<a href=showthread.php?s=&postid=8368875#post8368875 target=_blank>Originally posted</a> by sherm71tank
All this NW vs. Beckett talk inspired me. I switched out the 1/4" valve and air line I was using on my beckett with 3/8" and now I'm getting about 75 SCFH. So there! (Don't rain on my DIY parade to much guys!)

Wow, talk about cheap horsepower. What was your scfh before?

Do you have a feel for how the skimmer performs vs. before at a lower scfh?

sherm71tank

10/18/2006, 08:56 PM

It was about 50 before. Also, having owned DD skimmers before I can tell you that they have a significant impact on ORP where as the beckett, nw, venturi skimmers much less so. To soon to tell performance wise. I just got it done about 30 minutes ago.

hahnmeister

10/18/2006, 11:19 PM

<a href=showthread.php?s=&postid=8369019#post8369019 target=_blank>Originally posted</a> by alwest45
Hahn, thanks for the more detailed explaination. I'm still struggling with the contact time, i.e. the time the water spends in the skimmer, and I have difficulty understanding the theory behind why this is good. Of your hypothesis #1 (dwell time and contact time may be 1:1 interchangeable), wouldn't this be true for all skimmers and not just recirc skimmers. In fact, wouldn't this be also true for beckett skimmers?

Im just going to address this because Im sure the rest dont want to have to read through it, and the questions you raise are many of the same ones I have. But with just the one above, yes, if they are interchangable, it would apply to all skimmers, which is exactly the point. Most single pass skimmers... venturi, beckett, needlewheel... they put water and air in at the bottom, and there is a very short path for the water to go before it can exit, which due to water's nature, it does take this path of least resistance. With a recirc, the path is from the top of the skimmer all the way to the bottom... much longer to begin with, and there is the greater contact time because while the single pass skimmer might circulate water through the skimmer at 400-600gph, the recirculating skimmer will only move 1/4 of that maybe... longer time in the skimmer = more crud pulled out. Logical, and one could say whats the advantage between skimming old and new... but if the overall exposure time is cumulative, then the older water that is recirculated would have the advantage. Maybe...

Roland Jacques

10/19/2006, 05:38 AM

AL,
You picked some great skimmers choices, All of which will do a great job.

Shrem,
That sounds very cool. At 75 schf your skimmer needs a name now, how about the Sherm's Octobo-eckett skimmer. That's a lot of air you should post this.

Hahn,
I think AL wins, in his own example he disproves us. It’s kind of like this. You are the bubble and AL is the stubborn waste (strictly metaphorically :D ) . Other bubbles before you have bump into the waste with same info:spin1: :crazy1: :spin1: , but the waste keeps floating around, not bonding to it :bounce2: .

Most normal waste already let itself stick and is out of the way :beer: . So the other bubbles have moved on to be productive elsewhere :love2: . While you keep DWELLING with the stubborn waste, presenting the same info in many different ways and Examples and still, no sticking :bounce1: .

I guess the moral is like AL says, some waste going back into the system should be acceptable, so the bubbles can get on with trying to contact with new Poop.
Hmm I think he has got a good point .

(Pun intended):wave:

NoSchwag

10/19/2006, 07:59 AM

Here's something my old needlewheel couldn't do...

http://img134.imageshack.us/img134/5541/picture006zw2.jpg

You are looking at 1.5 days of SOLIDS collecting on my skimmer wall. It's all fish poop that you see. My tank stays particle free from my skimmer alone! Keep in mind my rocks are very clean

Another thing I couldn't do with my needlewheel is leave my house for more than a day without worrying if my collection cup would be full. The becket is VERY stable once running 100%. With my NW any little change in the tank would cause the skimmer to overflow, NOT TRUE WITH THE BECKET.

By matching my return pump to my skimmer pump, I skim my tank 9X's (give or take) pr. hour. This is something I couldn't do with a needlewheel or with a recirculating skimmer.

sherm71tank

10/19/2006, 09:22 AM

<a href=showthread.php?s=&postid=8370682#post8370682 target=_blank>Originally posted</a> by Roland Jacques

Shrem,
That sounds very cool. At 75 schf your skimmer needs a name now, how about the Sherm's Octobo-eckett skimmer. That's a lot of air you should post this.

I'll try to get a pic tonight. I do lose a little on the air meter though as I have to reduce from the 3/8" to 1/4" due to the outlet of the air meter. On a side note I underestimated the foam head it was going to produce. This morning I woke up to a flooded waste container and a collection cup spewing wet foam. I lowered the water level and hope it doesn't flood while I'm at work! Damn thats a big foam head!

JC VT

10/19/2006, 09:32 AM

By matching my return pump to my skimmer pump, I skim my tank 9X's (give or take) pr. hour. This is something I couldn't do with a needlewheel or with a recirculating skimmer.

I think many times the forest is lost in the trees when people are talking about how "efficient" a skimmer is. I would rather have my system be effective rather than having all these little "stubborn" molecules scrubbed out of the skimmer before the water exits.

Then again, "stubborn" molecules are something of a mystery. They're kind of some hoo doo, scary, unknown entity that must be skimmed out by a recirc with high contact time. FWIW, I would imagine wet skimming (with either type skimmer) would get larger solids/detritus out before it had a chance to break down and release "stubbon" molecules. Just like getting solid waste out prevents nitrates/phosphate build up by removing the source.

crab0000

10/19/2006, 09:52 AM

<a href=showthread.php?s=&postid=8371258#post8371258 target=_blank>Originally posted</a> by NoSchwag
Another thing I couldn't do with my needlewheel is leave my house for more than a day without worrying if my collection cup would be full. The becket is VERY stable once running 100%. With my NW any little change in the tank would cause the skimmer to overflow, NOT TRUE WITH THE BECKET.
This is completely and totally opposite from my experience with the two.

alwest45

10/19/2006, 09:52 AM

<a href=showthread.php?s=&postid=8370682#post8370682 target=_blank>Originally posted</a> by Roland Jacques

I think AL wins, in his own example he disproves us. It’s kind of like this. You are the bubble and AL is the stubborn waste (strictly metaphorically :D )

Hey! I'm listening over here!

Pyrrhus

10/19/2006, 10:13 AM

Ok, I'm gonna try this again.

If a given NW recirc pump pulls (just numbers- no meaning) 100 units of air and 200 units of water during normal operation, restricting the air input by 50 units will increase the water flow by 50 units. This cause the bubbles to spend more time in the reaction chamber because they are being dragged down by the intake of the recirc pump leading to a longer bubble dwell time and a thicker nog.

Many users of NW recirc skimmers have observed this. With no restrictions on the air intake the RPS-2000 at work has about 2/3's of the reaction chamber filled with bubbles. When the air is restricted the bubble cloud drops to fill about 4/5's of the reaction chamber. There is no additional air being added, just the entrainment from the recirc pump.

Covey

10/19/2006, 12:08 PM

Since this thread has had the two options explained at length i willl just include my experience.

Coralife 125 -> MRC MR-1 on PR rated pan world-> Reef Octo RPS-3000.

Each was an improvement on the last but I will probably never run a beckett again. Even being a big fan of MRC service and build quaility. The Reef Octo pulls 3X what the MRC did the RO using half the electricity, with far less noise. Also I noticed it was interesting that I skim wet, the beckett skims nearly clear skim with a bunch of particulate. Same wet setting on the big NW got me the same particulate but also got me farely brown liquid.

Independant of how the air bubble are being formed the Reef Octo style skimmers(RO, ASM, ER, H&S, Deltec...) are taking far better care of the bubble and the water.

sherm71tank

10/19/2006, 12:08 PM

HippieSmell

10/19/2006, 12:28 PM

One thing about the becketts that doesn't get mentioned often is the crud that collects on the inside of the riser tube. Even if I skim relatively wet, it still collects pretty fast. Even though the collection cup is tea colored, if I were to take all the crud in the riser and mix it in with the tea skimmate, I promise it will look like it came from a NW.

Roland Jacques

10/19/2006, 01:55 PM

<a href=showthread.php?s=&postid=8371959#post8371959 target=_blank>Originally posted</a> by alwest45
Hey! I'm listening over here! :lol: :lol: :lol:

Roland Jacques

10/19/2006, 01:57 PM

<a href=showthread.php?s=&postid=8373061#post8373061 target=_blank>Originally posted</a> by HippieSmell
One thing about the becketts that doesn't get mentioned often is the crud that collects on the inside of the riser tube. Even if I skim relatively wet, it still collects pretty fast. Even though the collection cup is tea colored, if I were to take all the crud in the riser and mix it in with the tea skimmate, I promise it will look like it came from a NW. so your calling that a good thing???:rolleye1:

Roland Jacques

10/19/2006, 02:02 PM

Roland Jacques

10/19/2006, 02:13 PM

<a href=showthread.php?s=&postid=8371258#post8371258 target=_blank>Originally posted</a> by NoSchwag

By matching my return pump to my skimmer pump, I skim my tank 9X's (give or take) pr. hour. This is something I couldn't do with a needlewheel or with a recirculating skimmer. thats very ture. Maybe, thats why, recirc's work better, Beckett's and NW's.

Roland Jacques

10/19/2006, 02:36 PM

<a href=showthread.php?s=&postid=8372102#post8372102 target=_blank>Originally posted</a> by pyrrhus
Ok, I'm gonna try this again.

If a given NW recirc pump pulls (just numbers- no meaning) 100 units of air and 200 units of water during normal operation, restricting the air input by 50 units will increase the water flow by 50 units. This cause the bubbles to spend more time in the reaction chamber because they are being dragged down by the intake of the recirc pump leading to a longer bubble dwell time and a thicker nog.

Many users of NW recirc skimmers have observed this. With no restrictions on the air intake the RPS-2000 at work has about 2/3's of the reaction chamber filled with bubbles. When the air is restricted the bubble cloud drops to fill about 4/5's of the reaction chamber. There is no additional air being added, just the entrainment from the recirc pump.

OMGoodness

1. you can accurately measure "air in suspension" by measuring the rise of the water column with no flow though being processed (a closed loop). this measurement will call air to water ratio.
in a 10" water column when you turn on the air it rises 1" that is a 10% air/water ratio. if you restrict your air water does increase like as you saw. And your bubbles will also go down further in the skimmer like you saw. What you did not see is your air /water ratio go down also. you can actually test this yourself and see. your air column will drop, this I have tested many times even in a controlled tank and gallons of test skimmate. one of the photos is still in my gallery.

All your doing is making more water cutting air back (Bad) & making more turbulance (also Bad)

2. if your octopus skimmer is stock you can improve your skimmate by simple adding your air silencer to the air hose (depending on your venturi) the reason this happen is restriction of the air causes smaller bubbles. I think this is due to it causing a more uniform air delivery (minimizing air surges that can be seen with flowmeters)

HippieSmell

10/19/2006, 04:25 PM

<a href=showthread.php?s=&postid=8373636#post8373636 target=_blank>Originally posted</a> by Roland Jacques
so your calling that a good thing???:rolleye1:
Good for maintenance, no. Good that I'm removing what looks and smells like baby crap from the system, you bet.

Oops, I forgot the obligatory rolleyes :rolleye1: . Much better.

crab0000

10/19/2006, 04:39 PM

My impression was all that crap cuts down on efficiency though, so unless you constantly keep it clean it won't be working optimally. Could be wrong though.

NoSchwag

10/19/2006, 05:53 PM

<a href=showthread.php?s=&postid=8371795#post8371795 target=_blank>Originally posted</a> by JC VT
FWIW, I would imagine wet skimming (with either type skimmer) would get larger solids/detritus out before it had a chance to break down and release "stubbon" molecules. Just like getting solid waste out prevents nitrates/phosphate build up by removing the source.

Exactly, and wet skimming is what, IMO, the becket does best. The needlewheel had a tendency of overflowing when I ran the water that high.

On top of that the weak needlewheel pump didn't create a solid MASS of upward moving bubbles like the pressure rated pump of the becket.

http://img234.imageshack.us/img234/5065/dsc0311010kd.jpg

Here is a great discussion we had about wet vs. dry:

http://reefcentral.com/forums/showthread.php?s=&threadid=801833

sherm71tank

10/19/2006, 05:54 PM

So, I wanted to get a true measurement of the SCFH on the beckett and took out the 1/4" adapter, wrapped some tape around the 3/8" hose and threaded that into the flow meter. I'll let the pic speak for itself. GO BECKETT!!!!

http://reefcentral.com/gallery/data/500/43852IM001325.JPG

NoSchwag

10/19/2006, 05:57 PM

<a href=showthread.php?s=&postid=8372917#post8372917 target=_blank>Originally posted</a> by Covey
the same particulate but also got me farely brown liquid.

That farely brown liquid is dissolved waste that your skimmer failed to get the first time around.

My skimmate is green with phyto.

NoSchwag

10/19/2006, 06:03 PM

<a href=showthread.php?s=&postid=8373751#post8373751 target=_blank>Originally posted</a> by Roland Jacques
thats very ture. Maybe, thats why, recirc's work better, Beckett's and NW's.

Think about it, which method is more effective at getting particles BEFORE they break down.. ...Recirculating the same water over and over again OR skimming a lot of different water.

My money is on getting as much particle filled water thru the skimmer as possible, as quick as possible ala becket..

The reason why recirc skimmers SEEM to work better, is because it's alowing crap to break down in the tank while it skims the same water over and over again. Think of it like fighting an uphill battle. Ask people with slow flow thru sump how good their skimmers work. There is a whole 123123908 page thread of people saying how much better their skimmers work.

The name of the game, IMO, is cleaning as much water as possible, as quick as possible.

NoSchwag

10/19/2006, 06:13 PM

<a href=showthread.php?s=&postid=8373675#post8373675 target=_blank>Originally posted</a> by Roland Jacques
I second this. they even make anti over flow accessories primarily for becketts and DD for that reason.

Actually it's just a "perk" so to speak. You can do the same thing to a NW if it's air tight.

NoSchwag

10/19/2006, 06:17 PM

<a href=showthread.php?s=&postid=8371957#post8371957 target=_blank>Originally posted</a> by crab0000
This is completely and totally opposite from my experience with the two.

I'm not gonna lie, it actually took me a long time to find the sweet "area" of the becket. But now that I know how to use my equipment, I can dial it in quick.

I set 2 other people up with beckets around here and they're both having the success with it that I am.

Roland Jacques

10/19/2006, 06:20 PM

<a href=showthread.php?s=&postid=8375271#post8375271 target=_blank>Originally posted</a> by sherm71tank
So, I wanted to get a true measurement of the SCFH on the beckett and took out the 1/4" adapter, wrapped some tape around the 3/8" hose and threaded that into the flow meter. I'll let the pic speak for itself. GO BECKETT!!!!

http://reefcentral.com/gallery/data/500/43852IM001325.JPG

AHHHH WOW. Come on brother wheres the new thread for this. Thats sucker SCREAMING!!!!! I need more info sherm. what size are the bubbles.

NoSchwag

10/19/2006, 06:26 PM

FWIW my air is cranked wayyyyyy down (2 out of 11 turns on a gate valve) for wet skimming.

sherm71tank

10/19/2006, 06:51 PM

<a href=showthread.php?s=&postid=8375468#post8375468 target=_blank>Originally posted</a> by Roland Jacques
AHHHH WOW. Come on brother wheres the new thread for this. Thats sucker SCREAMING!!!!! I need more info sherm. what size are the bubbles.

There will be no new thread. I've been building skimmers for years and built Beckett and Mazzei commercially for a while. I just didn't have time for it anymore. I honestly can't say what the bubble size is cause I can't see the outlet/diffuser in the skimmer because it is surrounded by foam. There is a 10" x 6" chamber full of solid foam. I am sure there are some that are larger than others with that much air vloume.

So anyway, where is the 100+ SCFH NW skimmer at?

Roland Jacques

10/19/2006, 06:58 PM

<a href=showthread.php?s=&postid=8375338#post8375338 target=_blank>Originally posted</a> by NoSchwag
Think about it, which method is more effective at getting particles BEFORE they break down.. ...Reticulating the same water over and over again OR skimming a lot of different water.

My money is on getting as much particle filled water thru the skimmer as possible, as quick as possible ala becket..

The reason why recirc skimmers SEEM to work better, is because it's alowing crap to break down in the tank while it skims the same water over and over again. Think of it like fighting an uphill battle. Ask people with slow flow thru sump how good their skimmers work. There is a whole 123123908 page thread of people saying how much better their skimmers work.

The name of the game, IMO, is cleaning as much water as possible, as quick as possible.

Good valid point, and it a good theory and could be true

EXCEPT for the FACT that when you run both recirc and single pass (of any skimmer) AT the same time on the same tank. the recirc always pulls out more and nastier smellier stuff.
You have to be able to explain this to support your argument. The high flow crowd keeps dancing around it.

jnarowe

10/19/2006, 07:16 PM

<a href=showthread.php?s=&postid=8375293#post8375293 target=_blank>Originally posted</a> by NoSchwag
That farely brown liquid is dissolved waste that your skimmer failed to get the first time around.

My skimmate is green with phyto.

Like this?

http://home.wavecable.com/~jrowe/skimmate%2072706.jpg

My skimmer uses 120W, no beckett, no needle wheel, gravity fed with 8 air stones.

You can see the buld pictures on my skimmer page (http://home.wavecable.com/~jrowe/skimmer.htm).

It's not pretty but it does an awesome job on my 1,200g system and the only power required is the Alita 100.

So my dear fools, there are many ways to skim a tank, and some are decidedly more electrically efficient than others. :D

jnarowe

10/19/2006, 07:19 PM

Oh yeah, and DIY RULES!!!

evilpsych

10/19/2006, 07:19 PM

good grief! i cant believe I just read all that..

Here's a thought..

Why doesn't one of our more well-funded members, conduct an experiment.

Take two skimmers, (non-recirc) one beckett, and one NW, that are sized for the same sized tank (heck, use the same brand/model/size of pump on each), and then run the water return from one as the water input to the other, and see which one catches more stuff that the other missed. Doesn't matter which one is first, but would seem to be a pretty good measure of which design is better. Surely someone can do this fairly readily on this board that has such a HIGH number of visitors at any given time..

Anyway.. my $0.02, I expect change back.. :bum:

NoSchwag

10/19/2006, 07:25 PM

<a href=showthread.php?s=&postid=8375729#post8375729 target=_blank>Originally posted</a> by Roland Jacques
Good valid point, and it a good theory and could be true

EXCEPT for the FACT that when you run both recirc and single pass (of any skimmer) AT the same time on the same tank. the recirc always pulls out more and nastier smellier stuff.
You have to be able to explain this to support your argument. The high flow crowd keeps dancing around it.

Can you show me a link, I'd like to check it out.

sherm71tank

10/19/2006, 07:28 PM

<a href=showthread.php?s=&postid=8375847#post8375847 target=_blank>Originally posted</a> by jnarowe
Like this?

http://home.wavecable.com/~jrowe/skimmate%2072706.jpg

My skimmer uses 120W, no beckett, no needle wheel, gravity fed with 8 air stones.

You can see the buld pictures on my skimmer page (http://home.wavecable.com/~jrowe/skimmer.htm).

It's not pretty but it does an awesome job on my 1,200g system and the only power required is the Alita 100.

So my dear fools, there are many ways to skim a tank, and some are decidedly more electrically efficient than others. :D

Ha ha ha ha ha!!! I love it!!! :beer:

NoSchwag

10/19/2006, 07:40 PM

Double Post

Roland Jacques

10/19/2006, 08:09 PM

<a href=showthread.php?s=&postid=8375687#post8375687 target=_blank>Originally posted</a> by sherm71tank
There will be no new thread. I've been building skimmers for years and built Beckett and Mazzei commercially for a while. I just didn't have time for it anymore. I honestly can't say what the bubble size is cause I can't see the outlet/diffuser in the skimmer because it is surrounded by foam. There is a 10" x 6" chamber full of solid foam. I am sure there are some that are larger than others with that much air vloume.

So anyway, where is the 100+ SCFH NW skimmer at?
90 scfh 54 - 60 watts. not quiet 100 scfh
http://www.it-kontaktmanagement.de/bm_action.swf
<a href=showthread.php?s=&postid=8375925#post8375925 target=_blank>Originally posted</a> by NoSchwag
Can you show me a link, I'd like to check it out.

Humm, you called me on it and i have no link, ill see what i can find.

JC VT

10/19/2006, 08:19 PM

the recirc always pulls out more and nastier smellier stuff.

Roland, we've already discussed how wet foam is better than dry "nasty" foam.

the recirc always pulls out more and nastier smellier stuff.

You have to be able to explain this to support your argument. The high flow crowd keeps dancing around it.

No one's danced around this. I've laid out a pretty clear argument that wet skimmate and high turnover is the best skimming for a clean reef tank. So has NoSchwag and others.

jnarowe

10/19/2006, 08:25 PM

<a href=showthread.php?s=&postid=8375873#post8375873 target=_blank>Originally posted</a> by evilpsych
good grief! i cant believe I just read all that..

Here's a thought..

Why doesn't one of our more well-funded members, conduct an experiment.

Take two skimmers, (non-recirc) one beckett, and one NW, that are sized for the same sized tank (heck, use the same brand/model/size of pump on each), and then run the water return from one as the water input to the other, and see which one catches more stuff that the other missed. Doesn't matter which one is first, but would seem to be a pretty good measure of which design is better. Surely someone can do this fairly readily on this board that has such a HIGH number of visitors at any given time..

Anyway.. my $0.02, I expect change back.. :bum:

That doesn't make any sense to me. I could see running the two on seperate gravity feeds and see which one pulls out the most stuff, but that is still subjected to variations in tuning and other variables. Running them inline would not give comparable results IMO becuase one would have first crack at the gunk.

Roland Jacques

10/19/2006, 08:37 PM

<a href=showthread.php?s=&postid=8376345#post8376345 target=_blank>Originally posted</a> by JC VT
Roland, we've already discussed how wet foam is better than dry "nasty" foam.

No one's danced around this. I've laid out a pretty clear argument that wet skimmate and high turnover is the best skimming for a clean reef tank. So has NoSchwag and others.

dude, talk about cut and paste. wet and dry had nothing to do with my statement. we all agree about wet and dry. you just danced around it again:dance:

"EXCEPT for the FACT that when you run both recirc and single pass (of any skimmer) AT the same time on the same tank. the recirc always pulls out more and nastier smellier stuff.
You have to be able to explain this to support your argument. The high flow crowd keeps dancing around it."

JC VT

10/19/2006, 08:48 PM

The nastier stuff is more concentrated, hence drier than true wet skimming. Take a look at NoSchwag's skimmate.

"EXCEPT for the FACT that when you run both recirc and single pass (of any skimmer) AT the same time on the same tank. the recirc always pulls out more and nastier smellier stuff.

You have to be able to explain this to support your argument. The high flow crowd keeps dancing around it."

No, we do not have to explain this at all. Recirc and high turnover are not mutually exclusive.

Roland Jacques

10/19/2006, 08:52 PM

No, we do not have to explain this at all. Recirc and high turnover are not mutually exclusive. :dance:

yes they absoluty are, that is the point.

2 identical skimmers
1 recirc the though put is 500 gallon per hour.
1 non recirc though put is 1000 gallons per hour = higher flow

why does the recirc pull out more and nastier stuff???

JC VT

10/19/2006, 08:58 PM

Roland, I run a Turboflotor on a 20L. I have about 7x my tank volume going through it. It is not mutually exclusive. Not one bit.

Manderx runs a massive recirc deltec skimmer on his 135 gallon. Almost entire overflow water goes through the skimmer. Where is it mutually exclusive?

2 identical skimmers
1 recirc the though put is 500 gallon per hour.
1 non recirc though put is 1000 gallons per hour

I'd like for you to show me exactly where I was comparing two identical skimmers. Bold and quotations would be nice.

I'm comparing two methodologies. Not two skimmers.

sherm71tank

10/19/2006, 09:03 PM

<a href=showthread.php?s=&postid=8376252#post8376252 target=_blank>Originally posted</a> by Roland Jacques
90 scfh 54 - 60 watts. not quiet 100 scfh
http://www.it-kontaktmanagement.de/bm_action.swf

I'm not sure what I am suppose to make of the video. I don't see anything there pertaining to watts or SCFH air.

Roland Jacques

10/19/2006, 09:05 PM

The man who can most easily test this for us is right here.

jnarowe has a airpump driven skimmer. he can run it at any through flow he wants.

jnarowe,
1. what flow rate do you run?
2. what happens to your skimmate production if you run 9times
3. your tank vollume through your skimmer?
4. whats your ideal setting?

JC VT

10/19/2006, 09:11 PM

The man who can most easily test this for us is right here.

Your questions, and subsequent answers, have nothing to do with methodology, Roland. You're talking about varying settings on an individual skimmer.

I'm talking about methodologies. Beckett is easier and cheaper for what NoSchwag and I advocate; high turnover and wet skimming. Especially for a 250 gallon SPS tank that Al wants to set up.

You'd need a heck of a recirc to accomplish the same.

JC VT

10/19/2006, 09:16 PM

You'd need a heck of a recirc to accomplish the same.

I think this monster would qualify :eek2: :eek2:

http://www.reefcentral.com/forums/showthread.php?threadid=732601

Roland Jacques

10/19/2006, 09:19 PM

sherm,
you dont see the flow meter? 2500+ lph=90 scfh

sherm71tank

10/19/2006, 09:30 PM

No, I really can't tell what it says. I would be down with one of them is they perform as we hope and they don't sound like freight trains and won't require constant cleaning and repair. Time will tell. For now, I'll stick with the beckett.

jnarowe

10/19/2006, 09:37 PM

<a href=showthread.php?s=&postid=8376735#post8376735 target=_blank>Originally posted</a> by Roland Jacques
The man who can most easily test this for us is right here.

jnarowe has a airpump driven skimmer. he can run it at any through flow he wants.

Not really. I just run it at max. I made little attempt to design this skimmer with flow in mind other than trying to emulate snailman's basic skimmer principles. I just wanted to get extremely good dwell time and had to work within the constraints of the space available.

The skimmer is 16" x 14" x 55"h and holds about 50g. The neck is 24" tall and I have 5" clearance from the ceiling.

The overflow is only about 5" higher than the skimmer body top and inlet. This gives me slow water throughput and sick dwell time. Sherman has seen it and can attest to that. I tend to run slightly wet but that often is a factor of salinity which I run on the high side at around 1.026 - 1.027.

I get approx. 4 gals. of very dark skimmate per week.

jnarowe,
1. what flow rate do you run?

Air= 100ltr/minute or flat out. I have been told that if I decrease (bleed) some air my bubbles would be smaller. What I have done is ordered extra large aquatic-eco fine pore stones. I will increase my stone surface area by 2.5x and report on the results. I believe it will decrease bubble size and increase density.

2. what happens to your skimmate production if you run 9times

I am not sure what you mean.

3. your tank vollume through your skimmer?

650g/hr or roughly 55%/hr

4. whats your ideal setting?

On. :D

Roland Jacques

10/19/2006, 09:42 PM

jnarowe
cool, i was only talking about water flow with the questions.

jnarowe

10/19/2006, 10:08 PM

<a href=showthread.php?s=&postid=8376986#post8376986 target=_blank>Originally posted</a> by Roland Jacques
jnarowe
cool, i was only talking about water flow with the questions.

I just open the valve and let it rip. Dale (tinygiants) was over one time and did a down and dirty test of flow and he came up with about 650g/hr.

I run a Hammerhead for return flow and figure with head loss I am getting about 4200g/hr through the overflow. I have two 2" return lines to the sump and one 1.5" line to the skimmer. With the drag of the BH screen, I figure it to be just about what Dale does. I had originally thought it was higher until I pulled off the screen to clean it and it was like flushing a toilet! :lol:

I am interested in Sherman's beckett designs as well as the Sequence NW and will try both. The only caveat is the question as to whether adding the electrical draw of the Sequence is worth the result.

Roland Jacques

10/19/2006, 10:25 PM

Originally posted by NoSchwag
Think about it, which method is more effective at getting particles BEFORE they break down.. ...Reticulating the same water over and over again OR skimming a lot of different water.

My money is on getting as much particle filled water thru the skimmer as possible, as quick as possible ala becket..

The reason why recirc skimmers SEEM to work better, is because it's alowing crap to break down in the tank while it skims the same water over and over again. Think of it like fighting an uphill battle. Ask people with slow flow thru sump how good their skimmers work. There is a whole 123123908 page thread of people saying how much better their skimmers work.

The name of the game, IMO, is cleaning as much water as possible, as quick as possible.
________________________________________

Good valid point, and it a good theory and could be true

EXCEPT for the FACT that when you run both recirc and single pass (of any skimmer) AT the same time on the same tank. the recirc always pulls out more and nastier smellier stuff.
You have to be able to explain this to support your argument. The high flow crowd keeps dancing around it.

JC VT

OK you see ,The topic I was Talking about with Noschwag was water flow in skimmers. JUST WATER FLOW. You might want to go back and read it again. Then again i might not have made that clear.

The idea that becketts are better because they flow more water was the argument that Noschwag made 9 times tank volume was the number he used. many other make that same argument. because of that high flow the skimmer could pick up stuff before it decade.....

So, with that said. If that is the logic here. Then two IDENTICAL skimmers one recirc (slower flow through 500GPH) and one non recirc (higher flow 1000GPH). By that logic the 1 flowing 1000 GPH should perform better Right?

My point is, the 500 gph skimmer always pulls out more skimmate and stinkyer skimmate. This is what I said gets danced around.

Then you talked about wet and dry foam … and this

“I'd like for you to show me exactly where I was comparing two identical skimmers. Bold and quotations would be nice.”

The Question, is mine. So you see, I am asking you to ask yourself this question. If more flow is good than how come less flow works better. Like Hahn said “the proof is in the pudding.”

JC VT

10/19/2006, 10:44 PM

I think many times the forest is lost in the trees when people are talking about how "efficient" a skimmer is. I would rather have my system be effective rather than having all these little "stubborn" molecules scrubbed out of the skimmer before the water exits.

:)

So, with that said. If that is the logic here. Then two IDENTICAL skimmers one recirc (slower flow through 500GPH) and one non recirc (higher flow 1000GPH). By that logic the 1 flowing 1000 GPH should perform better Right?

Yes, but this was never in contention. Al's acrylic cleaning analogy works here.

My point is, the 500 gph skimmer always pulls out more skimmate and stinkyer skimmate. This is what I said gets danced around.

Between two identical skimmers, sure. But we're not talking about two identical skimmers; this was never the basis for debate. We're talking about Al's choice to choose between any skimmer, of any type. We're talking about choosing TYPES of skimmers rather than a recirc Euroreef vs a non-recirc Euroreef.

I'm talking about methodology, and what skimmer best fits Al's interests of clean water for SPS.

sherm71tank

10/19/2006, 11:08 PM

Al, you still with us? This is for YOU after all!

Roland Jacques

10/19/2006, 11:36 PM

JC VT

If you don't understand the effects of different flows though the skimmer, water dwell time, you cant possible no how to compare the different skimmers.

You say this was never the basis for debate. I say it needs to be, and if you go back a few pages with Hahnmiester it was indeed a big part actually thourhout the thread

You say you agree that the recirc with the lower flow is better than the higher flow non recirc. Then you have to ask, if slow flow though is better than fast then is even slower better? how slow is the best flow for your tank. AND does that rule out the high flow beckett (non recirc) as the best choice.

We're talking about choosing TYPES of skimmers rather than a recirc Euroreef vs a non-recirc Euroreef”. Actually I was thinking of MRC recirc beckett vs a non recirc becket skimmer.

You say that this was never in contention. If flow water rate is not contention your not reading the same thread I am. Like I said I was talking to Noschwag

see you said "I advocate; high turnover", but you agree that the slower recirc's are better??? do you see what im getting at?

JC VT

10/19/2006, 11:58 PM

We're not talking about two identical skimmers, the only difference being recirc and not. You might be debating this, but I am not. We're talking about any type of skimmer, notably Beckett vs Needlewheel.

You say you agree that the recirc with the lower flow is better than the higher flow non recirc. Then you have to ask, if slow flow though is better than fast then is even slower better? how slow is the best flow for your tank. AND does that rule out the high flow beckett (non recirc) as the best choice.

Best for what. Bragging rights for lowest skimmer organic effluent? Or best for a reef tank. Unless you're turning your tank over many times through, you're not doing much. You're scrubbing water really clean... only to return them to a dirty tank. It's like having a ridiculously great washing machine... that only washes two shirts at a time, and then you throw them back into a dirty hamper. I don't know about you, but my laundry loads are larger than two shirts. Make your system effective.

Roland Jacques

10/20/2006, 12:02 AM

iI is so simple, the one that pulls out more stuff wins. you agreed the slower rcirc pulls out more stuff. 5 pounds of waste vs 3 pounds of waste day in and day out. Its just that simple.

you think it scrubing to get the last 10% out i say its scrubing to get the next 40% out. this is where we differ

JC VT

10/20/2006, 12:07 AM

iI is so simple, the one that pulls out more stuff wins. you agreed the slower rcirc pulls out more stuff. 5 pounds of waste vs 3 pounds of waste day in and day out. Its just that simple.

Now you're just getting silly.

We're not talking about two identical skimmers, the only difference being recirc and not. You might be debating this, but I am not. We're talking about any type of skimmer, notably Beckett vs Needlewheel.

Roland Jacques

10/20/2006, 12:14 AM

you think it scrubing to get the last 10% out i say its scrubing to get the next 40% out.

JC VT

10/20/2006, 12:21 AM

<a href=showthread.php?s=&postid=8377652#post8377652 target=_blank>Originally posted</a> by Roland Jacques
you think it scrubing to get the last 10% out i say its scrubing to get the next 40% out.

We're not talking about two identical skimmers, the only difference being recirc and not. You might be debating this, but I am not. We're talking about any type of skimmer, notably Beckett vs Needlewheel.

hahnmeister

10/20/2006, 12:24 AM

<a href=showthread.php?s=&postid=8375338#post8375338 target=_blank>Originally posted</a> by NoSchwag
The name of the game, IMO, is cleaning as much water as possible, as quick as possible.

The problem with this line of thinking is that it assumes that all that water you pass through that single-pass skimmer is being cleaned at least 50% in that small amount of time. In reality its only about what... 10% maybe? if that... So all you are doing is passing more water out of your skimmer before its cleaned.

Its like taking a UV sterilizer that is 18watts, rated for 100gph, and handles a 200g aquarium and thinking that by doubling the throughput you are increasing the handling to 400g... it just doesnt work that way.

And since when does more/darker proteins in the skimmer mean that there is more stuff in the tank that is breaking down? The longer that the waste spends inside of the tank, the less able you are to skim it out in the first place, as its converted to other materials that skimmers cant remove. Darker skimmate doesnt mean its from older material.

Roland Jacques

10/20/2006, 04:58 AM

<a href=showthread.php?s=&postid=8377626#post8377626 target=_blank>Originally posted</a> by JC VT
Now you're just getting silly.

Is it the word "pound" you think is silly or the skimmer that pulls out the most dry weight that is silly?

If you cant understand pounds it,s a unit of measurement, you may like oz's, or grams... Your just not getting my point are you?It's ok we can just agree that we have a failure to communicate.

NoSchwag

10/20/2006, 06:02 AM

<a href=showthread.php?s=&postid=8377688#post8377688 target=_blank>Originally posted</a> by hahnmeister
The problem with this line of thinking is that it assumes that all that water you pass through that single-pass skimmer is being cleaned at least 50% in that small amount of time. In reality its only about what... 10% maybe? if that... So all you are doing is passing more water out of your skimmer before its cleaned.

I'm still talking about particle skimming, not protien skimming. My skimmer is set up to strip the water of solids not protiens. I have about a 3 second dwell time in my skimmer.

NoSchwag

10/20/2006, 06:25 AM

Here is a video of my skimmer removing solids.

http://www.youtube.com/watch?v=cS-U1cmvxzI

Here are recent pics.

http://img209.imageshack.us/img209/568/skimmate001ei5.jpg

http://img86.imageshack.us/img86/4307/skimmate002zy1.jpg

NoSchwag

10/20/2006, 06:39 AM

<a href=showthread.php?s=&postid=8377688#post8377688 target=_blank>Originally posted</a> by hahnmeister

Darker skimmate doesnt mean its from older material.

How do you get that dark skimmate then? DOC's are Dissolved Organic Content. Let's remove as much as we can before it breaks down.

http://reefcentral.com/gallery/data/500/91795reflecphlemywtskim.jpg

crab0000

10/20/2006, 07:23 AM

I don't know why people think you can't skim wet with a NW without it overflowing. My ER did have that problem toward the end, but since I got my Deltec it hasn't happened yet and I can run it as wet as I want. I think this is due to better matching of the pump to the size skimmer it is used on. I get plenty of solids out with my NW as well. JME. Also, I think Bill Wann would be using becketts if they were superior since money is fairly plentiful for him and electricity shouldn't be a concern.

DKKA

10/20/2006, 08:49 AM

<a href=showthread.php?s=&postid=8376345#post8376345 target=_blank>Originally posted</a> by JC VT
No one's danced around this. I've laid out a pretty clear argument that wet skimmate and high turnover is the best skimming for a clean reef tank. So has NoSchwag and others.

I agree. This is the current thinking, and I may even agree with you. But, still, we should admit to ourselves that it is just speculation. Concentrations of skimmate will vary greatly from skimmer to skimmer and tank to tank. "Wet" skimmate from one skimmer/tank can easily be much more dilute than "wet" skimmate from another skimmer/tank. You just can't say that "wetter is better" With any skimmer it is necessary to achieve a balance of concetration, and volume. And just because a skimmer is skimming dry doesn't mean it removes no particulates. My needle wheel pulls out some detritus along with the other nasty stuff.

As far as removing particulates with a beckett versus dissolved organics with a needle wheel, even that is just theory. Even if you are effectively removing solids before they break down, you can bet that dissolved organics are still being produced within the tank from breakdown, but also other sources. Fish also pee, don't they. Not to mention hostile organics produced by algae, and corals. Are you certain you still want a skimmer that is optimized to remove solids versus dissolved organics? Escpecially considering that detritus can be a food source for corals, where exudates from algae can not.

Dan

NoSchwag

10/20/2006, 09:13 AM

I personally think there is a difference between "wet skimmate" and "wet skimming".

DKKA I use a UV also as well as wet skim.

JC VT

10/20/2006, 09:14 AM

And just because a skimmer is skimming dry doesn't mean it removes no particulates.

And just because a skimmer is skimming wet doesn't mean it doesn't remove proteins ;)

To me it's priority; particulates out first, DOC's out second. Can we agree that particulates should be exported rapidly instead of leaving in the tank to decompose?

FWIW, my skimmer running wet removes DOC's most of the time. But it is set up to get particulate crud out when it's there... like when I feed.

JC VT

10/20/2006, 09:19 AM

<a href=showthread.php?s=&postid=8378037#post8378037 target=_blank>Originally posted</a> by Roland Jacques
Is it the word "pound" you think is silly or the skimmer that pulls out the most dry weight that is silly?

If you cant understand pounds it,s a unit of measurement, you may like oz's, or grams... Your just not getting my point are you?It's ok we can just agree that we have a failure to communicate.

I'm speechless.

hahnmeister

10/20/2006, 10:49 AM

<a href=showthread.php?s=&postid=8378274#post8378274 target=_blank>Originally posted</a> by NoSchwag
How do you get that dark skimmate then? DOC's are Dissolved Organic Content. Let's remove as much as we can before it breaks down.

http://reefcentral.com/gallery/data/500/91795reflecphlemywtskim.jpg

Okay, if your skimmer pulls out all the solids in one pass... then the more power to ya, but most dont. But with this idea that older means darker... its still not right. DOC's arent older or newer. Urine and Ammonia fresh from a fish in the water is DOC.
You still havent shown anything to suggest that darker skimmate means its from older material. As far as Im concerned, the only differences between dark and light skimmate are the concentration (dry skimming vs. wet), and quality (a longer contact time will draw more amounts and possible types of proteins with more dwell time). Darker skimmate doesnt mean older, more broken down, etc. For the most part, the more broken down it is, the less able a skimmer is to grab it, as the ammonia and raw materials that skimmers try to extract get processed by other bacteria into other materials that skimmers dont deal with.... like nitrates and phosphates.

I can counter your claim of trying to remove as much as possible by running a skimmer with a fast turnover (3 second dwell). If our goal is to remove as much DOC as possible, wouldnt you want to run a lower throughput to capture more proteins. A 3 second dwell/contact time doesnt attract as many proteins, and so you are in effect processing very little of what is in your water, and dumping the rest back into the system. In this case, wouldnt the extra extraction of a recirc/countercurrent skimmer in fact be more of what you would want?

I also wanted to comment on the overflow issue. Beckett owners often swear off Needlewheels, and sometimes the other way around, because they used to have one that 'went crazy' after a dosing or feeding... and the cup would overflow. This can happen with any skimmer. The reasons why are not due to the method of bubble production, but due to the collection cup design. The diameter of the body, the diameter of the neck, and the height of the neck are the reasons for why an ASM might overflow and a Barr may not. Look at how different the risers are on these two types. A taller, narrower neck prevents these easy overflows. The overflow issue can be true of any poorly designed collection cup.

jnarowe

10/20/2006, 11:39 AM

I found that even with my giant riser I still got overflows, and I ultimately related that to salinity. When my tank was new and I didn't have the salinity issue down well I would get tank room flooding do to an overactive skimmer. When the skimmer would draw down the sump water and it was replaced with RO/DI, it would get even worse. I am not sure why this isn't mentioned in skimmer discussions, so maybe I am somehow off-base, but the two issues seemed to be related. When I feed my foam head collapses.

RichConley

10/20/2006, 11:58 AM

<a href=showthread.php?s=&postid=8357880#post8357880 target=_blank>Originally posted</a> by alwest45
I Rather than concentrate on trying to scrub the last bad stuff from your water in the skimmer and letting the easy to clean organics stay in your tank, it seems like you should get all the low hanging fruit first since it is quicker and easier. When you've gotten all the easy to clean molecules out (which I'm assuming is the majority of the organics that a skimmer can remove) then you can try to get more stubborn molecules (whatever they are) out.

Not at all Al. Your average, appropriately sized skimmer, will strip the "low hanging fruits" quite easily. What seperates a good skimmer from a poor skimmer, is its ability to pull out the tough stuff.

Think of it like this: The lower contact time skimmer will pull the easier stuff out faster, but when it finishes with the easy stuff, it can't do any more. The larger contact time skimmer wont pull out the easy stuff as fast, but it still pulls it out fast enough, and continues to work long after the other skimmer has shut down.

For an example, get two skimmers. The best would be getting the recirc, and non recirc model of the same skimmer. Set them up so that theyre running, in two seperate tubs, and tune them so they pull the same air. Pour a gallon of awful sludge into each tub. After an hour, the non-recirc will have pulled more skimmate than the recirc. After 12 hours, the recirc will probably have caught up, and after a week, will have pulled much more out.

Pulling the easy stuff out is just that: easy. Theres no reason to optimize your skimmer to do it, unless your skimmer is WAY undersized.

RichConley

10/20/2006, 12:03 PM

<a href=showthread.php?s=&postid=8375254#post8375254 target=_blank>Originally posted</a> by NoSchwag
Exactly, and wet skimming is what, IMO, the becket does best. The needlewheel had a tendency of overflowing when I ran the water that high.

On top of that the weak needlewheel pump didn't create a solid MASS of upward moving bubbles like the pressure rated pump of the becket.

http://img234.imageshack.us/img234/5065/dsc0311010kd.jpg

Here is a great discussion we had about wet vs. dry:

http://reefcentral.com/forums/showthread.php?s=&threadid=801833

FWIW, thats pretty much EXACTLY what the neck of my NW200 looks like (pulling 25-28scfh)

DKKA

10/20/2006, 03:17 PM

<a href=showthread.php?s=&postid=8379053#post8379053 target=_blank>Originally posted</a> by JC VT
And just because a skimmer is skimming wet doesn't mean it doesn't remove proteins ;)

Totally. I didn't mean to imply that it didn't. Most days of the week I don't have much doubt that a beckett is the more powerful skimmer. But other times I see people post pics of wet skimmate and I can't help but think 'wow, that looks like colored water.'
I don't think you can just continue to increase the flowrate thru a skimmer without eventually decreasing the performance due to the drop in dwell time. Without enough contact time some organics will never bond with a bubble and never be removed no matter how many times the water passes thru the skimmer.

To me it's priority; particulates out first, DOC's out second. Can we agree that particulates should be exported rapidly instead of leaving in the tank to decompose?

Well, you're talking to someone who has suffered more from washed out colors than algae problems. I haven't had real algae probs for years and years. So, rapid removal of particulates doesn't feel like a priority for me. I went a year and a half without touching my skimmer (other than to empty the cup) and at the same time bumping up my feedings, and I'm just now starting to get a little algae (still not problematic though) Colors and growth have improved as well, so I think I'll live with the algae I have for now. I did finally clean out the venturi, though.

Admitedly, if I was battliing algae then I would want to remove particulates as quickly as possible.

Dan

JC VT

10/20/2006, 07:14 PM

I can counter your claim of trying to remove as much as possible by running a skimmer with a fast turnover (3 second dwell). If our goal is to remove as much DOC as possible, wouldnt you want to run a lower throughput to capture more proteins. A 3 second dwell/contact time doesnt attract as many proteins, and so you are in effect processing very little of what is in your water, and dumping the rest back into the system. In this case, wouldnt the extra extraction of a recirc/countercurrent skimmer in fact be more of what you would want?

If you can turn your tank over enough through it, I guess. On the other hand, an influx of dirty tank water would give you dirtier water to skim, hence give you greater protein skimming... instead of trying to scrub that last little bit before it exits the skimmer. Did anyone pay attention to Al's acrylic cleaning analogy? Unless you run a very large skimmer, you cannot turn your tank over enough.

I don't think you can just continue to increase the flowrate thru a skimmer without eventually decreasing the performance due to the drop in dwell time. Without enough contact time some organics will never bond with a bubble and never be removed no matter how many times the water passes thru the skimmer.

We're talking about bubble dwell, yes? The same reason an MR-6 performs better than an MR-2?

Zephrant

10/20/2006, 09:52 PM

I see one tactic showing up pretty often in this discussion- Take a point, push it to the extreme then point out it's ridiculous there, so must not hold anywhere. i.e. "fast flow rates are good, so a skimmer with a 3 second water dwell time must be the best!", which is absurd.

Remember that skimmers work on curves- water flow, contact time, air flow, skimmer physics, organic levels and types, and tank dynamics are all somewhat intersecting curves. Pushing any one of these design goals to either end as a sanity check does not work on curves.

Some people are trying to map 6D space on to a 2D chart, and say "Here is the answer!". There is no one correct answer, or one perfect design for everyone. If there was, we'd all be building them.

Good discussion- watch the personal attacks though, we're doing pretty good so far so let's not derail it with occasional petty remarks.

jnarowe

10/20/2006, 09:56 PM

I did try to point that out but there was too much arguing! :D I wish Barr stuff was more readily available...

alwest45

10/21/2006, 07:59 PM

<a href=showthread.php?s=&postid=8377430#post8377430 target=_blank>Originally posted</a> by sherm71tank
Al, you still with us? This is for YOU after all!

sherm71tank, yes, I'm still here trying to make heads or tails of all of this. I am still salivating at your picture of the 100 scfh beckett skimmer. I'm starting to wonder if the RC500 is the right skimmer for me after all.

One conclusion I'm coming to is that it seems no one really knows many of the answers here but a lot of people have opinions. Many of the opinions are reasonable and based on their experience. But it still feels a little like a bunch of blind men trying to describe an elephant.

One conclusion I'm drawing is that there are substantial differences between skimmers of a particular design due to the design and engineering prowess of the skimmer vendor. An very well engineered NW skimmer can be light years better than a poor knockoff of the same skimmer by a vendor that doesn't really understand the design. When I hear people say things like "I had a <insert type here> style skimmer and it kept overflowing so all of those skimmers are crap" it is certain that they aren't dealing with a well engineered product. I tried to head off that problem in this thread by trying to limit the discussion to only very well engineered skimmers from established vendors. No DIY (since I can't buy one for my tank) and only the cream of the crop. Of course I didn't stop to think that almost no one thinks that they have a poorly designed skimmer. They blame it on the type of skimmer and then are happy to tell everyone that some other type of skimmer is much better. It is difficult to gather much useful advice from those kinds of postings.

I will say that I am troubled by the recirc vs. circ issue. I had hoped to come up with a strategy based on objective measurements, with scfh as the #1 driver, that would let me evaluate different types of skimmers (again only looking at the cream of the crop). And I expressly ruled out, in my evaluation criteria, energy efficiency. I too am looking for effectiveness so I am happy to have the best skimmer at improving the quality of my water even if it takes another 100 watts (which is still in the noise compared to my lighting bill). But the recirc/circ is making it hard to make progress on my task. And as far as I can tell no one knows what the curves for bubble dwell time look like, other than there is some assumption that 90-120 seconds will work well. Here's some more things that I don't understand yet:

- Take identical beckett skimmers like the Austin Oceans/Barr skimmers. A single beckett version does 45 scfh and has a bubble dwell time of X. Add the second beckett to the same skimmer and now the skimmer does 90 scfh and presumably does X/2 for bubble dwell time. I think the dual beckett will do a better job skimming my tank than the single beckett. I think you should be able to collect the data on these 2 skimmers and develop an algorithm that at least comes close to describing their comparable performance. But the more recirc argument is better prevents that.

- My current pick skimmer is the Euroreef RC500 with the new impeller. ER recommends 1-1.5x turnover through the skimmer. I have confirmed with ER that they still recommend that rate. I have a pump that will do 1.5X. But it sounds like there is a group that thinks that decreasing my turnover to less than 1X will result in better skimming. But if less than 300 gph is better, does that mean 200 gph is even better? How about 100gph? Even better yet? How about 1 gph? Is that still better than my 450 gph (1.5X) turnover? Unless I missed it, no one can point to any research or hard data to show this. Even the ER guys declined to tell me how they determined that 1-1.5X is best, although they stick with those numbers. So even if I'm trying to choose between needlewheel skimmers there is these very conflicting opinions as to what works better. And trying to rationalize beckett and NW performance looks even harder.

The good news is that as long as I stick to my "cream of the crop" list I probably will have good results no matter which skimmer I choose. I just wish there was more objective evidence and more hard data available to help.

I did ask the Austin Oceans guys why they can't do the 100 scfh that sherm71tank is getting and they confirmed that you have do up your airflow lines to 3/8" rather than 1/4". I have encouraged them to switch to 3/8" airflow lines. Seems like a pretty cheap way to double your scfh and they say their skimmer can handle the increased airflow. If they do that maybe I'll move back from NW to becketts...

Al