Which ro/di system is better [Archive] - Reef Central Online Community

Ironsheikh

03/13/2005, 10:29 AM

I got the 110 g a day from ebay as well-- didnt go for the drink tank and faucet version-- so I spent $100 about. just hook it up and put what you need. I have deionization and it works fine for me. I use it for drinking water as well -- I can really see a difference just by the color of my tea I drink. I use it for my marine tank and my betta water ... (I have 6 right now and they make a bubble nest by the next morning I change their water). Marine aquariums can nickle and dime you to death--save money when you can -- but if you have to have the name brand --go pay $200 extra and you don't even get the Deionization with it.

aquaman67

03/13/2005, 10:29 AM

The E bay systems use a membrane that is only 90 % efficient.

Other systems like Kent and Specta Pure use membranes that are 98 % efficient.

http://www.dow.com/liquidseps/prod/home_ele.htm (look at the bottom - 100 GPD membrane)

What is the difference?

The water that comes out is indeed 0 TDS because of the DI. You can put tap water into a DI and it will come out zero.

http://petsolutions.com/product.asp_Q_pn_E_17101175_A_Tap+Water+Filter_E_

The difference between the E Bay systems and the others is that while cheaper at first, the will use up DI cartridges much faster.

Don't believe me? Measure your tap water TDS. Take the line loose that goes into the DI from the RO membrane. Take another TDS reading there. If your tap is 200 TDS, your RO only will be around 20. With the name brand RO units that same tap water will be 4.

All the RO is is a mechanical filter for the DI. The RO rejects molecules based on size alone. The more you remove by RO the less you have to remove by DI.

People think because they paid a few dollars less on E Bay and their water comes out 0 TDS they think they got a good deal.

While crap isn't a word I'd use to describe the E Bay units, I myself use a Kent 60 GPD Hi-S. My membrane will be three years old in Oct and is still 97 % efficient. Your E bay unit couldn't do that when it was new.

Do any of the E Bay units list the efficiency of their RO membrane?

Kent does.

If your E Bay unit does please post it here, it'd like to see it.

aquaman67

03/13/2005, 10:56 AM

I found one myself. Here's the Filter Direct 110 GPD Aquarium model.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=20756&item=4364811737&tc=photo

I see now how they get around listing the efficiency of the membrane. It's there, you just have to do the math.

About in the middle of the page they give an example of tap water at 300 TDS. After RO they say it will be "around 20". That's only about 93 % efficient. (93 % would be 21 TDS)

With a 98 % efficient Kent unit that same tap water would come out of the RO at 6 TDS.

When my Kent membrane gets to 93 % efficient, I'd replace it.

vermonter310

03/13/2005, 11:08 AM

Originally posted by aquaman67
The E bay systems use a membrane that is only 90 % efficient.

Other systems like Kent and Specta Pure use membranes that are 98 % efficient.

http://www.dow.com/liquidseps/prod/home_ele.htm (look at the bottom - 100 GPD membrane)

What is the difference?

The water that comes out is indeed 0 TDS because of the DI. You can put tap water into a DI and it will come out zero.

http://petsolutions.com/product.asp_Q_pn_E_17101175_A_Tap+Water+Filter_E_

The difference between the E Bay systems and the others is that while cheaper at first, the will use up DI cartridges much faster.

Don't believe me? Measure your tap water TDS. Take the line loose that goes into the DI from the RO membrane. Take another TDS reading there. If your tap is 200 TDS, your RO only will be around 20. With the name brand RO units that same tap water will be 4.

All the RO is is a mechanical filter for the DI. The RO rejects molecules based on size alone. The more you remove by RO the less you have to remove by DI.

People think because they paid a few dollars less on E Bay and their water comes out 0 TDS they think they got a good deal.

While crap isn't a word I'd use to describe the E Bay units, I myself use a Kent 60 GPD Hi-S. My membrane will be three years old in Oct and is still 97 % efficient. Your E bay unit couldn't do that when it was new.

Do any of the E Bay units list the efficiency of their RO membrane?

Kent does.

If your E Bay unit does please post it here, it'd like to see it.

While I agree with all your points, When I replace my Membrane on my Aquasafe unit I'll put in a true RO one for $60-$70 and replace my DI cartridge for $14. Total investment of less than $200 over the course of 2-3 years. Can your Kent do that.:D

snorulz

03/13/2005, 11:28 AM

With the ebay units, all you have to do is ask for a "true membrane" even though what is in the unit is a real ro membrane anyway. Just ask for a 75 gal per day membrane and they will switch it for free (it is 98% efficient). Then you still save money and you have just as good a membrane as the kent unit. Only 2 companies make ro membranes.

aquaman67

03/13/2005, 11:36 AM

Originally posted by vermonter310
While I agree with all your points, When I replace my Membrane on my Aquasafe unit I'll put in a true RO one for $60-$70 and replace my DI cartridge for $14. Total investment of less than $200 over the course of 2-3 years. Can your Kent do that.:D

Is $219 close enough?

http://www.marinedepot.com/md_viewItem.asp?idproduct=KM1433

Plus if you buy from MD they give you 15 % off replacement cartridges.

aquaman67

03/13/2005, 11:38 AM

Originally posted by snorulz
With the ebay units, all you have to do is ask for a "true membrane" even though what is in the unit is a real ro membrane anyway. Just ask for a 75 gal per day membrane and they will switch it for free (it is 98% efficient). Then you still save money and you have just as good a membrane as the kent unit. Only 2 companies make ro membranes.

If you can get a true membrane, then that's a better deal.

snorulz

03/13/2005, 11:39 AM

So you are saying this unit will work for 2-3 years without ever having to change any filters??? I don't think so.

aquaman67

03/13/2005, 11:43 AM

No, I've replaced my filters once and I have a set on order as I expect the DI exhaust soon. How much will you be spending on DI cartridges over the three years I wonder?

snorulz

03/13/2005, 11:59 AM

I have spent 236.50 (including the unit) and i have enough to change evey pre and post filter and di media every 6 months for the next 2 1/2 years. Being my di chamber holds 16 oz, it will last quite awhile.

Ironsheikh

03/13/2005, 12:00 PM

big dave, trust your gut -- my set up works for me/ the other guy's works for him--a damn brita is better than the water I had before. Lol

aquaman67

03/13/2005, 12:13 PM

Originally posted by Ironsheikh
big dave, trust your gut -- my set up works for me/ the other guy's works for him--a damn brita is better than the water I had before. Lol

Well said.

The differences are were discussing (not argueing) about are really pretty small.

What I wonder about is why you have to "ask for the good stuff".

Why don't they just sell the 75 GPD units?

snorulz

03/13/2005, 12:19 PM

I guess because 100 gpd looks better to most people than 75 gallon per day. The membranes cost the same so thats not why. Truely im not sure.

Studioksr

03/13/2005, 08:51 PM

I've been looking at the compact Home/Reef 50 gpd units from Air Water Ice -- is there something comparable on Ebay?

I want it to fit under my kitchen sink. I've also been looking on Ebay, but they don't post sizes.

jamesBS

03/14/2005, 07:00 PM

my aqua-safe from ebay came with a applied membrane.from applied membranes inc model no m-t1812a100 but evan if your ro is100% what about whean you feed your fish the food is full of stuff.i think 98% is good

Reefmaniac1

03/15/2005, 02:06 AM

www.airwaterice.com. Walter builds a unit that can't be beat.

Rickster88888

03/15/2005, 07:06 AM

Hi all,

Pls pardon me for my ignorance as i am thinking of getting a DI unit for my water change. Since everyone is in this topic here so i thought that it will be better posting the question here...

From what i read above it seems that if i just run the tap water through a filter canister with DI resin would be a waste of $$ as it will exhaust much faster... Question now is that should i connect another canister with a 5 micron filter before it?

Should i add extra canister like carbon to it too? Will be fixing up the whole unit at my uncle's hardware store so things would be pretty cheap for me :) . Too bad he know nothing about clean water.

Cheers man~

aquaman67

03/15/2005, 07:15 AM

It would be better the have the water go through a 5 micron filter and carbon before it gets to the DI. Better, but not much better.

Having it go through the first two and then through a RO would be best.

frank2926

03/15/2005, 07:46 AM

Just one more point on the ebay unit. I had 2 of these that lasted about 1 year each before the membrane went. Before I bought my next one I did a little investigating. The reason my membranes went was because of the prefilter sizes. The ebay unit used a 5 m sediment then 2 5m carbons. The problem is that the membrane itself is 1m and with all prefilters being 5m they would become clogged quickly and then would cut down the pressure to the ro membrane quickly. The combination of low preasure and sediment as large as 4m getting to it and clogging it. Also no reverse flush ......
What you need along the line of filters is to start with is a 10m sediment then go to a 5m carbon then to a 1m carbon. This way you are decreasing sediment size from filter to filter . If you start with a 5m sediment you will quickly lose pressure and clog the Ro membrane sooner In my case I change the sediment every 2-3 months. Then in 2-3 months I change the sediment and the first carbon , then at the 9 month mark I am changing all filters plus DI.
www.airwaterice.com gives you a 3 year warranty on the membrane. I think in this hobby we quickly learn not to skimp on most things .....how many protein skimmers have you bought?

TroyPierce

03/15/2005, 08:49 AM

I bought a six stage unit off of eBay for a couple reasons: price, lack of experience and price. I used it for a year and stil had TDS of 1.

I ordered replacement filters since it was past time and got an upgraded system at a good price. I now have a 5 micron sediment, then a 1 micron sediment, then a .6 micron carbon block then the 75 GPD RO filter and finally a huge DI cart. The sixth stage was a taste filter for drinking water and I'll put one of those just before the faucet.

I got all my filters from Buckeye at a great price. I also got the DI unit from them. It's refillable and in a standard 10 inch cart.

http://www.buckeyefieldsupply.com/showproducts.asp?Category=3&Sub=1

All of the filters cost about $60 plus $28 for the DI add-on.

Rickster88888

03/15/2005, 09:04 AM

Thankz for the reply aquaman...

Can someone pls tell me would the flow rate be greatly reduced if i install a RO unit?...

From what i understand having the 5 micron filter + the DI unit would not reduce the pressure of the water significantly...

Cheers~

AZDesertRat

03/15/2005, 10:37 AM

Rickster,
You are actually asking about two different things. Pressure and flow are not the same. A DI cartridge and prefilters will not significantly reduce either flow or pressure. An RO/DI will reduce both flow and pressure but will produce water with a TDS at or near 0 for months or more depending on water conditions compared to a DI alone which might only last days or weeks at best. Prefilters only catch latge suspended particles and carbon does the same plus removes some things like chlorine and volatiles. DI resin will only adsorb so much which is why we put an RO in front of it to act as a prefilter if you may. I tested my water last night and found raw water TDS to be 473, RO product water at 11 and DI product at 0. My DI cartridge is 8 weeks old and I have made about 150 gallons of water with it so far. If I did not have the RO and used only DI I most probably would have only produced around 30 gallons before exhausting the resin. At anywhere from $5 (bulk purchase) to $25 per refill cartridge it adds up very quickly.
Do you know your raw water condition? You really need to start there to determine what type of filtration is best for you. I would suggest an RO/DI unit with either a pressure tank or a storage vessel and float switch of some type.

Rickster88888

03/15/2005, 11:09 AM

AZDesertRat thank you sooo much for explaining the whole process !!! :)

Finally understand how it works....

Hmmm guess I will spend much more eventually if i try to save some $$$ initially by not getting the RO..

Thank you once again... :)

bboersma79

03/15/2005, 11:17 PM

Hey, I am a newbie and I am going to get the Typhoon III from www.airwaterice.com, looks like a great system with all the options I would like, and the price is still reasonable.

Reefmaniac1

03/16/2005, 12:09 AM

Like I said before, Walter builds a system that can't be beaten. The Typhoon/Typhoon III are all that I will recommend.

fishman_CT

03/16/2005, 01:12 PM

I have to second that about the Typhoon III. It is by far the best unit I have ever owned. I have the 75 GPD membrane and I have a TDS of 4 before going into the DI. Can't beat that! And the price ain't bad either. I think I paid around $200 for mine. Easy to hook up, it comes with a free float and also a free TDS meter. In addition to all these reasons, they have been in business for a while. 5 years from now you can call him and say you are having problems and he will help you. 5 years from now, you think you will be able to find these guys on Ebay?
Probably not.

Stevan

03/16/2005, 01:23 PM

Originally posted by aquaman67
The E bay systems use a membrane that is only 90 % efficient.

Other systems like Kent and Specta Pure use membranes that are 98 % efficient.

http://www.dow.com/liquidseps/prod/home_ele.htm (look at the bottom - 100 GPD membrane)

What is the difference?

The water that comes out is indeed 0 TDS because of the DI. You can put tap water into a DI and it will come out zero.

http://petsolutions.com/product.asp_Q_pn_E_17101175_A_Tap+Water+Filter_E_

The difference between the E Bay systems and the others is that while cheaper at first, the will use up DI cartridges much faster.

Don't believe me? Measure your tap water TDS. Take the line loose that goes into the DI from the RO membrane. Take another TDS reading there. If your tap is 200 TDS, your RO only will be around 20. With the name brand RO units that same tap water will be 4.

All the RO is is a mechanical filter for the DI. The RO rejects molecules based on size alone. The more you remove by RO the less you have to remove by DI.

People think because they paid a few dollars less on E Bay and their water comes out 0 TDS they think they got a good deal.

While crap isn't a word I'd use to describe the E Bay units, I myself use a Kent 60 GPD Hi-S. My membrane will be three years old in Oct and is still 97 % efficient. Your E bay unit couldn't do that when it was new.

Do any of the E Bay units list the efficiency of their RO membrane?

Kent does.

If your E Bay unit does please post it here, it'd like to see it.

Very well put.

Take a look here http://airwaterice.com/ the TyphoonIII is a rnice package and even includes a TDS meter, float valve saddle valve and wrench.

PS-My Typhoon arrived with a major leak. I emiled Walter that night by 8am the next day I had an return email. They had alreadt shipped a replacement and a pre-paid ups label.

I got the replacement and went on a 2 week vacation the next day. I didn't return the leaking unit for 3 weeks. Never heard a peep from them demanding it's return.

A class act.

fishman_CT

03/16/2005, 01:34 PM

Walter is a very nice guy. He will do what ever he can do to help us consumers. He gets my vote everytime! He even gives $10 off if you find an error in his website. I found 1 and got $10 off. There are some more errors out there. Find them and receive the $10 off. You will NOT be disappointed!

TroyPierce

03/16/2005, 02:57 PM

Originally posted by fishman_CT
Walter is a very nice guy. He will do what ever he can do to help us consumers. He gets my vote everytime! He even gives $10 off if you find an error in his website. I found 1 and got $10 off. There are some more errors out there. Find them and receive the $10 off. You will NOT be disappointed!

Can't agrue with support. But lest someone imply that the eBayers DON'T offer a similar level, I can testify that they do. For $86 (plus $25 for the TDS meter), I got a six stage unit (well the sixth stage was the taste filter with was not necessary) with a 2.5 gallon storage tank and a lea free sink faucet, heavy duty needle valve, drain saddle clamp, auto shutoff, filter wrench and 10 extra feet of color-coded hose. It also came with a flush valve to clean the RO filter.

If asked, he would have switched out the 100GPD with a 75.

Knowing what I do now, if there were a weakness to this unit, it's the DI cart and storage tank size. My unit didn't have a refillable DI cart (and it was mounted horizontally instead of being one of the 10" canisters). However, $28 from Buckeye took care of that.

The tank was 2.5 gallons and a larger one would have been nice.

The current units have a 16 oz, refillable DI cart (still horizontally mounted) and a 4 gallon storage tank. Here's an ended (not the one I got, unfortunately) eBay auction for reference:

AquasafeSystems RO/DI (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=20684&item=4331120874&rd=1)

The issue is the workmanship and support. There aren't that many makers of the canisters and the RO filters are made by the same company.

Others may have had bad experiences with some of the eBay vendors, but personally, I've found Ed at Aquasafe to be very reliable and responsive.

fishman_CT

03/16/2005, 03:22 PM

How often do you have to change your filters? I beleive mine are good for 9000 gallons of water! That's a lot of water. So if you take into account the $114 cost difference for the price of the unit, minus a free $25 TDS meter, and a free $25 float valve, that's a $64 cost difference. Now you say that you have a 16oz refillable DI cartridge. How much does it cost for the media to ill it and how long does it last? If it costs less than $64 to get 9000 gallons filtered, then it is worth it to buy the cheaper model. I just don't think you would be able to filter that much water with that particular unit. I could me wrong. Does anyone know the answer to this?

TroyPierce

03/16/2005, 05:41 PM

The answer really depends on how "bad" your water is. The 9000 gallons is a guesimate at best. As the commercial says, "your mileage may vary".

Everyone's filters are "better" than everybody elses. I've been using my eBay "crappy" filter for over a year and still have TDS of 1. I don't really HAVE to change my filters now but I wanted to change things around and "upgrade" to a 75 GPD RO filter.

I just bought a full set of filters from Buckeye for:

5 micron sediment filter: $2.70
1 micron sediment filter: $3.00
.6 micron Carbon Block filter: $9.50 (supposed to be 20K gallons)
75 GPH RO membrane: $45.00
DI cart and housing: $38.00 with refillable cartridge.
Refills for DI are $38.99 for 5 lbs or $12 for enough for one refill.

These prices are all from Buckey Supply http://www.buckeyefieldsupply.com/showproducts.asp?Sub=1&showspecials=1 if you check around, you might be able to get better DI pricing, I don't know.

The point is, I didn't have to spend the $60 (not including DI housing and cart) on day one. Most vendors tell you to replace your filters every year so I took the opportunity to take advantage of the knowledge I gleened from others here on RC.

I also, BTW, bought a new TDS meter from Marine Depot. It's a dual unit that installs in-line. This way I can monitor the output of the RO filter AND the output of the DI with a flip of the switch.

I guess MY message, for what it's worth, is: if you're more comfortable buying a Kent or one of the name brands, do so. But from my experience, there's nothing wrong with the eBay units, at least the one I got from Aquasafe.

snorulz

03/16/2005, 07:09 PM

Originally posted by fishman_CT
I have to second that about the Typhoon III. It is by far the best unit I have ever owned. I have the 75 GPD membrane and I have a TDS of 4 before going into the DI. Can't beat that! And the price ain't bad either. I think I paid around $200 for mine. Easy to hook up, it comes with a free float and also a free TDS meter. In addition to all these reasons, they have been in business for a while. 5 years from now you can call him and say you are having problems and he will help you. 5 years from now, you think you will be able to find these guys on Ebay?
Probably not.

Ebay companies are just as much companies as air water ice is. They have just as good a chance in being around in 5 years as air water ice. You have nothing to back up this claim.
I want to add i do think the air water ice units are great but i also think there is nothing wrong with an ebay unit with the 75gpd membrane in it.

Tras

03/16/2005, 08:05 PM

Can someone explain this table for me? Both the 75 and 100 look the same.

http://www.appliedmembranes.com/tfe.htm

fishman_CT

03/16/2005, 08:45 PM

I do not disagree that the units you buy from Ebay are not as good. I am just saying from my past experiences. Davebell24 was asking when he origianally started this trheat about which unit we thought would suit his needs. I did not agree with him at first when he started to talk about Ebay crap, because I am a member of Ebay and do a lot of transasctions on there. What I am trying to say is that for the price of $300+ dollars, there are better alternatives than spending all that money on a unit. We are all spending roughly the same price for our units. I am just trying to help Davebell24 from my experiences.

davebell24

03/16/2005, 09:23 PM

WOW, If I offended anyone out there, I"m Sorry, Just had bad expieriences before with e-bay and didn't want to spend money on something that I might regret later. I rather spend the money and not have to worry about the product and the customer service later/.

snorulz

03/16/2005, 09:28 PM

The ebay units use dow membranes. The 75 and 100 are different from dow. Look up dow filmtec membranes on appliedmembranes website.

AZDesertRat

03/16/2005, 10:12 PM

Applied Membranes rates their membranes differently than Dow Filmtec does. Although Applied buys their raw material from Dow they say they produce 100 Gallons Per Day at 65 PSI pressureand 96% rejection. Dow Filmtec on the other hand rates their RO membrane at 75 GPD at 50 PSI and 98% rejection. It is essentially the identical membrane as the Applied but is rated at a more realistic pressure that most of us will see in our homes. Dow Filmtec also makes a 100 GPD but they do not claim it is a true RO membrane but a "high flow membrane" and therefore rate it at 100 GPD at 50 PSI but only with 90% rejection rate or efficiency where their others are 98% efficient.
Most homes in the United States get their Municipal water at around 60 PSI at their water meter normally. Figure in seasonal usage, line sizes, restrictions and time of day your pressure probably truly is close to the 50 PSI that Dow Filmtec rates their membranes at. So in essence what Applied claims to be a 100 GPD is really a 75 GPD.
Look here at the Dow Filmtec chart and you will see what I am talking about.

http://www.dow.com/webapps/lit/litorder.asp?filepath=liquidseps/pdfs/noreg/609-09010.pdf

If you plot out the pressure on a 75 GPD to 65 PSI you will see it will produce 100 GPD but that is not a realistic pressure in most cases. The other factors are temperature, which is rated at 77 degree water which most of us don't have for most of the year if at all and raw water quality which is rated at 250 mg/L or PPM which again doesn't quite fit in a lot of cases. My raw water is between 550 and 800 TDS in Phoenix.

All in all, your best bang for the buck is a true Dow Filmtec 75 GPD RO membrane regardless of whether it is in an E-Bay unit or any other unit out there. Personal experience steers me away from most e-bay vendors just because I can't get them to answer e-mails or technical questions, but there are always exceptions to the rule I suppose.
I have personally dealt with Walter at Air Water & Ice, John at Aquatic Reef Systems, Russ at Buckeye Field Systems, Watts Premier here in Phoenix and Charles at Spectrapure and would not hesitate to recommend any of them in a heartbeat. Customer Service and a long term relationship are key components when I do business with someone and I know they will all be there next year when I need to ask a question or buy something additional.

snorulz

03/17/2005, 09:10 AM

The 100 gpd filmtec ro membrane is a "true" ro membrane. It does exactly what ro membranes do. It is just set up to move more water which is why its called high flow. Yes it takes out less crap but regardless it is still a ro membrane. Now if your definition of a "true" ro membrane is 98% rejection rate than i can't argue with what you think because the 100gpd doesn't not have this. But how you are saying it is very misleading, you make it sound like its not a ro membrane and this is untrue. Dow does call it an ro membrane, and if you want proof i will take a picure of the membrane with the original sticker saying RO membrane, not high flow membrane.

AZDesertRat

03/17/2005, 09:19 AM

I'd like to see the picture. Dow never stares it is an RO membrane and does not market it as such. Look at the link I provided and read it word for word, the 100 never mentions RO.

fishman_CT

03/17/2005, 09:36 AM

Hey Davebell24, what are your thoughts about which unit to get? You are the thread starter, and I think we are getting off topic. I am sure that all the units we have forementioned are good. What are your thougts?

snorulz

03/17/2005, 09:54 AM

Here is a pic of the membrane from aquasafesystems ebay auction. I will take a picture of my actual membrane but it will take a few days.
100gpd ro membrane (http://www.aquasafecanada.com/ro%20membrane.jpg)

snorulz

03/17/2005, 09:57 AM

Is this proof enough that dow calls it a ro membrane?
100 gpd membrane (dow website) (http://www.dow.com/liquidseps/prod/tw30_1812100.htm)
100gpd data sheet (http://www.dow.com/webapps/lit/litorder.asp?filepath=liquidseps/pdfs/noreg/609-00382.pdf)

snorulz

03/17/2005, 10:04 AM

I do want to apologize to Davebell24, sorry for helping this get in another direction. At least we are still talking about ro systems. If you don't want to mess with ebay then i recommend AirWaterIce systems.

TroyPierce

03/17/2005, 10:20 AM

I'm curious... The spec sheets for the RO membranes all refer to the rejection rate as SALT rejection. All of the threads I've read here on RC talk about the 100GPD as removing 90% of the "bad stuff", so if you start with a TDS of 400, you end up with TDS of 40.

But does the 90% "salt rejection" equate, generally, to 90% removal of other minerals? AZDesertRat, as a Water/Wastewater Consultant, what are your thoughts? Have we been anxious over something that doesn't make a difference, since few, if any municipal water systems have salt in their water?

snorulz

03/17/2005, 10:26 AM

Salt is a term used in chemistry to describe a solution that will completly ionize in water (completly dissolve) meaning most filters have a very hard time removing it. There are other salts than the one our water softener puts in and what we use on the table, or our fish swim in, that contaminate our water.

AZDesertRat

03/17/2005, 03:39 PM

Snorulz,
The picture you provided is an Applied membrane not a Dow. As stated before, the Applied is basically a Dow 75GPD which Applied re rates at 65 PSI rather than Dows 50 PSI. It is not a Dow 100 GPD "High Flow" drinking water element.
Look here:
http://www.dow.com/liquidseps/prod/home_ele.htm

Dow does not refer to their 100 as an RO element and even provides a seperate data sheet for it. It is not NSF 58 approved and is considered by Dow to be a nano filter with .001 removal versus the 75 with .0001 removal.

Troy, salt is just a general term for solutes in water as snorulz said.

Here is a list of things removed from Dows website.
http://dow-water.custhelp.com/cgi-bin/dow_water.cfg/php/enduser/std_adp.php?p_faqid=252&p_created=1043797236&p_sid=KCEKREAh&p_lva=433&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MTY2JnBfcHJvZHM9JnBfY2F0cz0wJnBfcHY9JnB fY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD10eXBpY2FsIHJlbW92YWw *&p_li=&p_topview=1

snorulz

03/17/2005, 04:15 PM

FILMTECTM reverse osmosis membrane elements for home drinking water are the industry's most reliable

Taken directly from the link you provided.

snorulz

03/17/2005, 04:24 PM

hmmm, well ill be damned, so i really have a 75 gallon per day membrane? Mine is identical to the one in the pic, i just looked. So i should be getting 98% rejection rate, correct? I will have to check that out. Well if this really is a 75 gallon perday ro membrane at 50 psi then you don't need to change anything from aquasafesystems.
My point about the dow filmtec membrane is why do they say filmtectm reverse osmosis membrane element then?

snorulz

03/17/2005, 04:36 PM

Are you sure about the appliedmembranes 100gpd ro element actually being a 75? I am getting exactly 90% rejection rate out of mine, its only a month old so i know its not bad. hmmm, now im really confused.

langjc

03/17/2005, 05:08 PM

Just buy the ro/di from airwaterice.com and be done with it. Top notch customer service. This is a fact that noone can take away

AZDesertRat

03/17/2005, 05:17 PM

Applied Membranes information is a little hard to decipher compared to Dow Filmtecs. While they say they use Dow materials for their membranes they state a 96% rejection vs Dows 98% or 90% in the case of their 100, they also rate them at 65 psi versus Dows 50 psi.
I tested my output from my Dow 75GPD last night when I got home and its right at 97% with a year old membrane which sees lots of use between aquariums, tortoises, home drinking and ice maker, not to mention I also home brew beer and make a 5 gallon batch almost every weekend.
Out of curiosity what is your waste to product ratio? I use a fixed flow restrictor which is at 6 to 1 and it seems to help with Phoenix hard water. It can't hurt to flush the heck out of the membrane when it running, I also do not use a flush kitas I have mixed feelings on their usefulness.

snorulz

03/17/2005, 05:28 PM

Mine is 4 to 1

bboersma79

03/17/2005, 05:41 PM

I just bought mine from buckeyefieldsupply, was $150...pretty much the same unit offered at airwaterice for $200...

aquaman67

03/17/2005, 07:56 PM

Hey AZDesertRat,

First, I want to say I've learned a lot about RO/DI from you.

I have a a question.

Does higher pressure make a RO produce more water but at a lower efficiency?

I'm running mine at about 125 psi and I get 97 % efficiency.

I'm just wondering if I should lower the pressure a tad.

AZDesertRat

03/17/2005, 08:11 PM

I don't think pressure (within reason) affects the product water quality. When I say within reason Dow says their membranes will operate at up to 300 psi. which is much higher than the housings or your plumbing will withstand. The advantage to higher pressure is you get greater output which is a problem most of us would like to have.

You might try looking at the Dow Answer Center here:
http://dow-water.custhelp.com/cgi-bin/dow_water.cfg/php/enduser/std_alp.php?

and see if they have any articles on that subject. 97% efficiency is pretty
One advantage of buying membranes from somewhere like Spectrapure is you have the option of having a membrane hand tested in their facility and guaranteed to produce a certain quantity and quality. You pay for this service but it sometimes is worth it.
I had my first 75 GPD membrane tested at the Watts Premier facility here in Phoenix and found it actually produced closer to 90 GPD at the recommended pressure, temperature and raw water TDS. Of course that was under laboratory conditions but it proved to be a good membrane that lasted 16 months of heavy use which is good for Phoenix water.

BTW I just left a Municipal Water Production position after almost 18 years and went to work for an Environmental Engineering firm as a Senior Operations Specialist working on projects for the very cities I once worked for!

aquaman67

03/17/2005, 08:33 PM

Originally posted by AZDesertRat
BTW I just left a Municipal Water Production position after almost 18 years and went to work for an Environmental Engineering firm as a Senior Operations Specialist working on projects for the very cities I once worked for!

Sweet, you can't beat that.

I've only been getting paid to play with water for about 7 years.

snorulz

03/17/2005, 11:04 PM

I contacted ed from aquasafesystems and he says the membrane should have 95% efficiency, so it is not a 90% efficiency dow filmtec 100gpd membrane, i wonder why i am not getting 95%.

aquaman67

03/18/2005, 05:48 AM

Originally posted by snorulz
I contacted ed from aquasafesystems and he says the membrane should have 95% efficiency, so it is not a 90% efficiency dow filmtec 100gpd membrane, i wonder why i am not getting 95%.

If your unit is new, maybe the membrane isn't fully saturated yet. It takes quite a bit of use to get the membrane fully saturated. If you have made over 50 gallons of product water, I'd say that's enough and not the cause.

Maybe someone put a sticker on a different membrane?