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Dustin1300
03/23/2012, 09:57 PM
I'm looking for some advice on how to make my RO/DI unit more efficient. Previously I had a no name RO/DI unit and I've since upgraded to a Vertex Puratek 100 GPD unit. That being said, I'm in the process of a large system build and I'm much more serious about the efficiency of my RO/DI unit. (Currently have 285 gallons of system online and will be adding a 600 gallon DT and additional sump in the future)

That being said, I have always went by the rule that I change out my filters as soon as TDS hits 1. With a fresh set of filters and DI (minus membrane), I got about 250-300 gallons out of the first set of filters and most of that was a continuous cycle when I was filling the system with RO/DI water. Below is my current specs and questions.

Specs:
- With booster pump consistent 50 psi (Seems low compared to others)
- Stock 100 GPD membrane
- Tap water w/ TDS of 395-445
- 5 TDS before DI
- 0 TDS after DI (BRS Color Changing DI (http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/replacement-filters-and-di-resin/deionization-resin/nuclear-grade-color-changing-di-resin-1-5-gallons-7-5pounds.html))

Questions:
- Considering making the unit a dual membrane unit and changing out flow restrictor and making it a dual 75 GPD unit rather than single 100 GPD membrane? Anyone done this with unit and have feedback? What type of psi would I need to function this way as I realize current pump is not up to that job? (Kit I'm Considering (http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/ro-di-accessories/150-gpd-water-saving-upgrade-kit.html))
- Pump upgrade recommendation on above? (This one? (http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/ro-di-accessories/aquatec-8800-booster-pump-kit.html#))
- Should I go to dual stage DI?
- Will I see sufficient savings on filters if I go with jumbo (20") filters over standard (10") filters or is it more of a convenience factor? Good place to pick up canister to hold the larger filters if I went this route?

I know that I have lots of questions but trying to put an order in with BRS on Monday to get this thing kicked in shape:)

http://i395.photobucket.com/albums/pp32/Dustin_1300_Reef/photobucket-2303-1332556257808.jpg

Darth Vedder
03/23/2012, 10:37 PM
I have the same unit and am extremely happy with it. I will Definately be following along as I'm curious as well

I will say my pump on the stock unit keeps it close to 90 psi

Dustin1300
03/23/2012, 11:03 PM
I have the same unit and am extremely happy with it. I will Definately be following along as I'm curious as well

I will say my pump on the stock unit keeps it close to 90 psi

I'm curious whether it's my pump or the water to the pipe. I'm previously tied into a 1/2" copper pipe with a saddle valve that is positioned on the top side so it does not clog valve. Maybe I should consider teeing off 3/4" copper but not sure that's really going to help me as 1/2" copper should have no problem supplying a 1/4" line!

DHyslop
03/23/2012, 11:09 PM
Are you saying that you change out all your filters as soon as the output creeps above zero TDS?? That's pretty wasteful right there.

Darth Vedder
03/23/2012, 11:12 PM
I used a washer "Y" hose that splits the cold feed to my utility sink and the other to a 3/4" threaded hose valve that feeds my unit

My water pressure in my house sucks too. The saddle valve probably isn't helping matters

Dustin1300
03/23/2012, 11:15 PM
Are you saying that you change out all your filters as soon as the output creeps above zero TDS?? That's pretty wasteful right there.

That might be wasteful to some but it's much easier to prevent unwanted particulates in the RO/DI water rather than trying to pulling it back out of the aquarium later.

DHyslop
03/23/2012, 11:37 PM
That might be wasteful to some but it's much easier to prevent unwanted particulates in the RO/DI water rather than trying to pulling it back out of the aquarium later.

Which particulates are these, pray tell?

This is not the way these systems are designed to run. The RO and the DI do the heavy lifting and the prefilters exist only to extend their lives. Replacing any part of the system before it is clogged or spent does nothing to increase the quality of the product water.

Remember that each filter is designed to take out a different thing. If you have little iron in your water but a lot of phosphate your sediment filter might be good as new for months while you burn through a DI every week. In that case changing the prefilter every week accomplishes nothing except helping somebody at BRS make a boat payment.

I have the opposite problem: My water is pretty good but the city pipes are a mess. I go through a sediment filter every week but my DI lasts forever. I've made about a thousand gallons of water and not only is output TDS still zero, but there isn't even a hint of color change anywhere in the resin.

bertoni
03/23/2012, 11:58 PM
I agree that the sediment filters don't necessarily need to be replaced on the same schedule as the DI filters. They are doing different tasks.

In theory, the 75 gpd membranes can be more effective than the 100 gpd models, and thus save on DI media. Your reported TDS out of the RO membrane is very good, though. I am surprised it's that good, actually. I might double-check that result.

I don't know about the cost effectiveness of the larger filters, but you likely could save some money by packing your own DI cartridges, although it needs to be done with some care.

Dustin1300
03/24/2012, 06:50 AM
Thanks for the comments Jonathon. I already refill the DI cartridges to save a little bit of money and use the method outlined in the following clip from BRS: Refilling DI Cartridges (http://www.bulkreefsupply.com/store/video?file_name=96)

As far as the TDS after the RO, it starts at about 10-12 when system first starts filtering and once it's been going for a few minutes it settles down to 6. My previous unit did similar at my other house and I had a about the same TDS at the tap. (These readings are after my water softener too) I test TDS after DI using the mounted meter that came with the unit and I use a dual TDS meter (http://premiumaquatics.com/aquatic-supplies/HM-DM-1.html) from PA to check what's coming in the tap and how the RO is doing. From what I've read this little meter is as accurate as any of the others @ +-2%.

At what point should I replace the RO filters? Should I wait until TDS reaches 10, 15, etc???

Thanks again!

Randy Holmes-Farley
03/24/2012, 09:17 AM
I would replace the DI as soon as the TDS rises above 0 ppm. But the carbon and sediment filters can last much longer. Leave the sediment filters in place until the pressure drops noticeably or the effluent rate gets too low.

Dustin1300
03/24/2012, 10:25 AM
Thanks Randy. Glad the expert aligns with my TDS opinion as I don't like using anything with any TDS in my tanks:) I typically don't change out the RO filters until the TDS before DI stages starts to creep up since Carbon/Sediment filters are fairly cheap to come by.

What do you think about the dual 75gpd membrane idea? I'd think my ratios/output would be much better but not sure how much it would effect filter life?

tmz
03/24/2012, 12:51 PM
I agree the tds post di shuld be 0 as this tds will hold higher concentrations of harmful materials than post ro tds.

As for efficiency and peace of mind a second di cansiter is a worthy addition ,ime.

An in line dual tds meter plumbed between the two di canisters can read the tds out of the first and second . When the tds out of the first di canister in line goes over 0, I change the resin( I use non color changing resin) in the first in line di canister ; move the second di canister to first in line ,and; the newly filled one into second position. This way I know I'm changing resin at the right time, not prematurely or too late, and ensuring tds post di is consistently 0.

bertoni
03/24/2012, 06:40 PM
I don't know enough to comment on using 2 75 gpd membranes. I'd change the RO membranes as soon as I got a significant increase in TDS, which in this case probably would be 10 TDS after the startup period. Also, the output rate might decline, I guess.

Sport507
03/24/2012, 09:07 PM
Dustin, 1/2 feed to the unit isn't the probalem considering that is't reduced reduced to 1/4" or 3/8" anyway. I think it's your boster pump.

I run dual 75gpd membranes and I keep my pressure at 95psi with my boster pump. I make one gallon in about 10 minutes.

You going to the INDMAS frag swap in April?

Buckeye Hydro
03/25/2012, 06:42 AM
A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the usable life of these two filters is to use a pressure gauge to identify when pressure reaching the membrane starts to decline. This is your indication one or both of the filters is beginning to clog.

Also be cognizant of the chlorine capacity of the carbon block. A good 0.5 micron carbon block for example will remove 99% of chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons.

Regarding your RO membrane and DI resin, use your TDS meter to measure, record, and track the TDS (expressed in parts per million) in three places:
1. Tap water
2. After the RO but before the DI
3. After the DI.

The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 parts per million (ppm). Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about getting that TDS reading down to somewhere near zero?

If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block filter (collectively called “prefilters”) do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO housing and you'll see it is still approximately 400 ppm.

The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 90% (i.e., they reject 90% of the dissolved solids in feed water). So the purified water coming from your 100 gpd membrane would be about 40 ppm (a 90% reduction). Filmtec 75 gpd (and below) membranes produce less purified water (aka “permeate”), but have a higher rejection rate (96 to 98%). The life span of a RO membrane is dependent upon how much water you run through it, and how dirty the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the total dissolved solids (TDS) in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce less water as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the 40 ppm water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, you know that your resin needs to be replaced. Sometimes people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin “dirty” water. This will exhaust the resin quicker than would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal.

Russ

Buckeye Hydro
03/25/2012, 06:44 AM
Questions:
- Considering making the unit a dual membrane unit and changing out flow restrictor and making it a dual 75 GPD unit rather than single 100 GPD membrane? Anyone done this with unit and have feedback? What type of psi would I need to function this way as I realize current pump is not up to that job?
remember that what folks call "waste water" really would be better thought of as "flush water" in that this water serves the important purpose of internally flushing the surface of the semipermeable membrane to keep the membrane from fouling/scaling.

When you configure a system with two membranes in series (the waste from the first membrane going to the "in" port on the second membrane), for this discussion let's say it's two 75 gpd membranes, the system behaves like you have a single long (75 gpd x 2) 150 gpd membrane.

Now - if you use a proper flow restrictor, that is, one for a 150 gpd membrane, you'll have about a 4:1 waste to product ratio. Sounds familiar, right?

If however you don't change the flow restrictor - meaning you keep using the same restrictor you were using when you just had one 75 gpd membrane, then you'll see a waste to product ratio much lower than 4:1. But remember that the recommendation for a ~4:1 ratio comes from the membrane manufacturer. They are telling you that you need about a 4:1 ratio to keep the membrane flushed and keep the membrane from fouling or building up scale. Run the system with a lower ratio and you will foul/scale the membrane(s) quicker than would have otherwise been the case.

Instead of adding a second membrane to lower that ratio, you could have just changed out your flow restrictor ($4) instead. A much less expensive approach to get you to the same endpoint in terms of saving on waste water.

Now, to confuse things just a bit. Filmtec specs call for the 4 to 1 ratio on the basis of assumptions about the water that will be supplied to the membrane. If you have very soft water you MAY be able to get a decent service life from the membrane running at a ratio lower than 4 to 1 (e.g., 3 to 1). Remember that the waste water from the first membrane is about 25% harder than your tap water.

Bottom line: If what you are after is reduced waste water, experiment with a different flow restrictor for $4 instead of messing around with a second membrane plumbed in series.

As a side note, you can also lower the ratio by increasing the pressure delivered to the membrane (with a booster pump), because flow restrictors are sized assuming you are providing factory spec conditions (50 psi and 77 degrees for Filmtec membranes). Increase the pressure and you'll drive more water through the membrane and viola - less waste water. But as I mentioned above, if you do this (just like over-restricting a membrane) - the lower the waste to product ratio, the shorter the lifespan on the membrane.

Makes sense?

Russ

Dustin1300
03/25/2012, 07:30 AM
Dustin, 1/2 feed to the unit isn't the probalem considering that is't reduced reduced to 1/4" or 3/8" anyway. I think it's your boster pump.

I run dual 75gpd membranes and I keep my pressure at 95psi with my boster pump. I make one gallon in about 10 minutes.

You going to the INDMAS frag swap in April?

I plan on being at the swap. Do you have the stock booster pump on yours?

Dustin1300
03/25/2012, 07:41 AM
Buckeye, thanks for the amazingly thorough response. I guess you've questioned my end goal and after looking at all the factors, I want something that produces water a bit faster, less waste water, but the most cost effective in the long run if that makes sense? ;)

I see on your site that you have a 150 gpd membrane. With what you said earlier putting two 75 gpd membranes in series is like having a 150 gpd membrane so does it make better sense to have dual 75 membranes or a single 150 gpd membrane?

Sport507
03/25/2012, 09:31 AM
I plan on being at the swap. Do you have the stock booster pump on yours?

I have the Aqucatec CDP 8800 that BRS sells. It has a pressure adjusting screw on top that uses a 1/16" allen wrench to adjust it. By keeping my pressure 90-95 psi I don't have as much flush/waste water. Probably about 2.75-3:1 Waste - product.

I also have a flush valve on my unit that helps keep the membranes clean. I flush the membranes about 2 minutes before and after each use.

I'll be at INDMAS too.

Dustin1300
03/26/2012, 07:28 AM
Sport, what size of flow restrictor do you have?

Sport507
03/26/2012, 10:00 AM
Sport, what size of flow restrictor do you have?

Dustin, I知 using the one that came with the single 75GPD membrane. Understand even though I知 now running two 75 membranes, I知 running them in series not one single 150GPD. I have a stage 5 system and I get 2 TDS after RO and of course 0 after DI.

Hope this helps.

Dustin1300
03/26/2012, 11:28 AM
Sport, thanks for the reply and was not following the earlier flow restricter reference because the way I see them plumbed. I already put an order into PA for $700 this morning so for the sake of my marriage i'm going to continue researching the topic.

I did go ahead and order second stage of di, 7.5 pound of di, refillable cartridge, and 75 gpd membrane/restricter from brs as I needed plumbing parts. We will see what I get with that setup and i'm going to take apart booster pump to see what happens and if anything seems odd. If that does not pan out I will order booster pump and second membrane which will be must for 600 gallon dt I will bring online.

Sent from my DROID BIONIC using Tapatalk

Buckeye Hydro
03/26/2012, 05:14 PM
I知 now running two 75 membranes, I知 running them in series not one single 150GPD.

two 75's plumbed in series = one 150 gpd membrane, in respect to what flow restrictor to use.

Russ