BAH! 35 ppm from RO membrane. How long do yours last?

FishTruck · 09/17/2009, 02:08 PM

Well...

I think I know why my SPS has been looking so mediocre lately.

Tap water in - 127 ppm
RO water out - 35 ppm

Maybe there is some municipal water supply nastiness that is making things tough on my SPS.

I last replaced my two membrane system Feb of this year. As I have been combing over every parameter trying to figure out why my acros have been doing so poorly lately, I didn't even think to check the RO system.

How long do you guys get your RO membranes to last on your setups? How often do you test?

Oh yea...

Good thing I basically quit running carbon a couple of months ago... just to make it worse!

rolodex1 · 09/17/2009, 03:10 PM

I had the same problem the last two weeks. My sps corals were doing really well (lots of new growth). Then within a couple of weeks they started to have tissue degradation and have since lost one, I think. I checked everything: lighting (bulbs 6month old), Flow (OK), H20 parameters OK), and then I noticed my RO water ppm were 6-7. I have always been under the impression anything under 10ppm was ok. I ordered all new membranes including the TMD (sp) the real expensive one. (I have a 50gpd unit). I changed out the filters and the TDS meter read 0ppm. So, I did a 35g water change on the 125g and again a week later. I have a noticeable change for the better since. Not all the way healed, but they are looking much better. And to answer your question, I last changed out all the filter about 6 months ago. My advise and what I'm going to do from now on is check the TDS meter and never let it get above 0ppm. Hope this helped!

Shawn

FishTruck · 09/17/2009, 03:15 PM

Thanks rolodex for sharing.

I just hooked up an inline TDS monitor to check weekly with other water parameters.

Hopefully, my SPS will come back now.

NanoReefWanabe · 09/17/2009, 09:08 PM

i was under the impression your RO membrane should last indefinately, if the prefilters are maintained properly, and the water pressure and temperature are within specifications...my filmtec75 has been going for over a year now with 0TDS...

FishTruck · 09/18/2009, 09:12 AM

Yes, that was the impression I was under too.

Which begs the next question... how often do you change your pre-filters?

RandalB · 09/19/2009, 03:22 AM

Membranes should be good for a minimum of 2 years.. Fish, you have a problem with your system there if you are eating them faster than that...

What's the details on your system? Maybe we can run down what the problem is...

Also, 127 from Downer's Grove seems way low for your feed water. Are you on a well or being supplied from Lake Michigan?

RandalB

kenrooke · 09/19/2009, 05:28 AM

i change my prefilters every three months as to preserve the life of the membrane which if hooked up to a soft water system could last up to eight years according to the manufacturer.i have also added a deionizer for extra assurance.in addition i have a hand held tds meter to compare from my outline meter.i measured the inline household water at 560 tds.our water in the waterloo region is often called liquid cement.lol .

Buckeye Hydro · 09/19/2009, 10:18 AM

Quote:

Originally posted by FishTruck
Well...

I think I know why my SPS has been looking so mediocre lately.

Tap water in - 127 ppm
RO water out - 35 ppm

Maybe there is some municipal water supply nastiness that is making things tough on my SPS.

So you have an RO system, rather than an RODI, right?

What is your waste water to purified water ratio? This may provide a hint re your membrane not being fully seated.

What is your water pressure at the membrane? Your pressure may be so low that your membrane can't do what you're asking of it.

Are you letting the system run for a while (2 minutes+) before taking your tds readings?

Russ @ BFS

FishTruck · 09/19/2009, 01:14 PM

Guys, thanks for the help.

It is RODI. Spectra pure unit with sediment pre filter, carbon filter, two RO membranes and DI.

Randal B.

I was surprised my tap water TDS was that low too. It is Lake Michigan water. I tested with two TDS meters and got the same results.

Buckeye...

Waste water is 275 ppm. Purfied is 27 ppm after running for about five minutes. This suggests the membrane is not functioning correctly, No?

I was not waiting long enough to take the reading when I got 35 ppm. Also, during the ATO part of the units duty... it might be creating water for a minute or so at a time. I should add a timer to make sure it runs in longer intervals... right?

Water pressure is 50 psi.

Buckeye Hydro · 09/19/2009, 01:59 PM

Let's back up a little.

Its important to check your TDS on an RODI system in THREE locations:
Tap: you reported 275 ppm
RO: ???
DI: you reported 27 ppm

So we know for sure at this point that your DI resin is shot and needs to be replaced.

I need the TDS in the RO water to see how your membrane is working.

What is the ratio of waste water to purified water? We're talking about volume here. Should be something like a 4:1. So with about 8 identical drinking water glasses lined up in front of the system, and your waste tube in one hand and your DI "out" tube in the other hand, how many glasses do you fill with waste water in the time it takes to fill up one glass with DI water?

And you are right - you want the system kicking on less frequently rather than more frequently. There are a number of ways to do this.

Russ @
Buckeye Field Supply

FishTruck · 09/19/2009, 04:07 PM

OK Recap.

Tap 127 ppm
RO 47 ppm
DI 27 ppm
(waste water is 275 ppm, but I don't think you need this value)

pressure 50 psi

waste flow rate 425 ml per min
produce flow rate 500 ml per min - WOOPS!

Buckeye Hydro · 09/19/2009, 08:09 PM

AH-HA! So its likely that the membrane isn't fully seated, or the RO membrane housing has an internal crack/chip allowing waste water to flow out of the permeate port.

Pull the membrane out and check the condition of the o-rings on the far end of the stem. Shine a flashlight in the housing and check the condition of the cup into which to membrane seats.

Russ @
Buckeye Field Supply

Russ

FishTruck · 09/21/2009, 09:56 PM

SO... I put in two new membranes. For testing purposes, the DI is not hooked up.

First run I got this.

Tap 127 ppm
RO 15 ppm

pressure 50 psi

waste flow rate 425 ml per min
produce flow rate 500 ml per min - WOOPS! This is still bad.

So. I figured it must the the resistor tube. Sure enough. This was too long and also slightly corroded. Per the table, I cut it down to 1 inch, then 3/4 inch and still the best ratio or waste to product I could get was about 2.5/1.

So. I tossed the resistor tube in the trash and used a JG gate valve instead... dialing the resistance up until the desired 4 to 1 ratio was achieved.

Final run.

Tap 127 ppm
RO 10 ppm - rejection rate is about 92%. Not that great... but I will live with it.

pressure 40 psi (lower now)

waste flow rate 1300 ml per min
produce flow rate 320 ml per min - about 120 gallons per day. This is what I would expect with 40 psi.
ratio = 4 to 1 = good

So, final assessment is that my restrictor tube was too long and or clogged, this is probably what trashed my RO membranes so quickly. Next, I have to wonder if the test runs I did today ruined my brand new membranes? Also, should I plan to use my gatevalve to control resistance from now on? Any downside to that?

I have redone the plumbing so I can easily check waste to product flow rates as part of routine monitoring.

Wow. More than I had bargained for!

rbnice1 · 09/21/2009, 10:45 PM

Can you post some pics showing how you have redone it to check your ratio easier?

I mean did you put something inline that allows you to measure both?

Toddrtrex · 09/21/2009, 11:59 PM

Do you know what RO membrane you have?

On average they are going to be rated for 90% rejection rate, or 96-98% rejection rate. I have a Dow FilmTec 75 GPD membrane and last time I checked (( about a month ago )) I was getting 97% rejection rate from it.

For reference, my tap's TDS is about 150, I am in Lombard, near 88 and 355 so not that far from you. But, there seems to be a bit more sediment in my water, after 3-4 months my pressure goes from around 60 PSI down to 50, so I change my pre-filter more often. After DI, I end up with 0 TDS. My RO membrane is about 2 years old.

Tadashi · 09/21/2009, 11:59 PM

Mine would last about 18-24 mo before resulting in 2-3 ppm TDS water. I installed two sediment filters on my system one at 1 micron and then .5 micros, and a carbon at .5. I changed out my sediments every 6 mo since they were so cheap. Carbon out every 8-12 mo.

my pressure was at 80 psi. I did not measure between chambers but this would probably have saved me some change outs.

Buckeye Hydro · 09/22/2009, 03:18 AM

FishTruck - I don't remember - are your membranes plumbed in series - i.e. waste from the first feeding the second membrane, with only one restrictor found after the second membrane?

Assuming the answer is yes, and with two 75 gpd membranes, you functionally have a single 150 gpd membrane.

I would not use that ball vlave as your restrictor long-term, but rather get a capillary flow restrictor designed for a 150 gpd membrane. They are very inexpensive.

Its very unlikely that you damaged the membranes much with your test runs. The buildup of scale in the membranes takes some time.

If you only have 40 psi at the input of the first membrane, you probably only have 32 psi at the input to the second membrane - not enough.

You have some options to address that if you'd like.

Russ

FishTruck · 09/22/2009, 08:28 AM

Final product after DI is 0 ppm. I was just about out of fresh water.

rb nice -

I just put a T and some shut off valves at the RO output and RO waste - so I can divert the flow of both into buckets to measure flow rates... without disconnecting anything. Until I get a new $3.99 capillary tube, I am using a gate valve to control resistance. I use these for my calcium reactor to control flow and was luckly late last night to have one lying around.

Todd RX - I have two 150 gpd 98% rejection rate RO membranes from Bulk Reef supply. I replaced two DOW filmtec 150 gpd 98% membranes. I was hoping for a better rejection rate than 92%. Maybe they need to run longer? They were getting better with each test. I was just in your neck of the woods at Tropiqautics the other day.

Tadashi - the schedule you use is about what I was assuming I would use.

Buckeye - my membranes are plumbed in series as you have described. I have two 150 gpd membranes. Will get a new capillary tube. I guess with borderline pressure... I might be better off with a booster. Would this improve the rejection rate? I set the ATO to a timer to fill my resevoir only overnight, hopefully in one long run, to avoid rapid on / off cycling.

Buckeye Hydro · 09/22/2009, 06:09 PM

You won't have luck using an Aquatec 8800 booster pump to drive the two 150 gpd membranes. You could experiment with some of the other brands, but be careful what you buy if you stray into the low cost imports.

Rejection rates improve with higher pressure.

Russ

FishTruck · 09/23/2009, 05:24 AM

OK, I am really learning a lot here.

Let's say I keep burning through my DI resin more quickly than I want.... but, I also want the ability to make at least 100 gpd (in a pinch).

Would I do better with a booster and two 75 gpd membranes, or, to try and find a booster that would work with two 150 gpd membranes.

Or, another way to ask the same question... what is the technical issue with boosters and two 150 gpd membranes versus two 75 gpd membranes?

I notice that most systems sold with boosters have only single membranes.

Buckeye Hydro · 09/23/2009, 06:29 AM

Aquatec 8800 booster pumps are good only up to 120 gpd, assuming a 20% recovery (4:1 wate to permeate ratio).

If all you need is 100 gpd, go with a single 75 gpd membrane with pressure boosted to 90 psi. With 65 degree F water, you'll produce about 115 gpd, with a high rejection rate.

Russ

Buckeye Hydro · 09/23/2009, 06:30 AM

Fish - just noticed your "Department of Redundancy Department." What a hoot!

FishTruck · 09/23/2009, 10:39 AM

Thanks!

I will see how these membranes do... and if I keep burning through DI resin, go with a single 75 gpd and a booster.

Toddrtrex · 09/23/2009, 10:47 AM

Quote:

Originally posted by FishTruck
Thanks!

I will see how these membranes do... and if I keep burning through DI resin, go with a single 75 gpd and a booster.

You have a bigger tank then I do, but I am guessing that your water pressure is pretty similar to mine (( Downers is just South of me )). I can fill up a 5 gallon container in just under 2 hours. I have a 75 GPD membrane and no booster pump.

FishTruck · 10/07/2009, 07:36 PM

OK. Follow up.

I swapped my two 150 gpd membranes for a single 75 gpd and added a booster, bringing the pressure up to 80 psi. Also, carefully adjusted until my waste to RO ratio was just exactly 4 to 1.

Now, my RO output is 0 ppm. WOW! DI resin should last a little longer now!

09/17/2009, 02:08 PM	#1
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	BAH! 35 ppm from RO membrane. How long do yours last? Well... I think I know why my SPS has been looking so mediocre lately. Tap water in - 127 ppm RO water out - 35 ppm Maybe there is some municipal water supply nastiness that is making things tough on my SPS. I last replaced my two membrane system Feb of this year. As I have been combing over every parameter trying to figure out why my acros have been doing so poorly lately, I didn't even think to check the RO system. How long do you guys get your RO membranes to last on your setups? How often do you test? Oh yea... Good thing I basically quit running carbon a couple of months ago... just to make it worse! __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/17/2009, 03:10 PM	#2
rolodex1 Registered Member Join Date: Jan 2007 Location: Clearwater, FL Posts: 1,297	I had the same problem the last two weeks. My sps corals were doing really well (lots of new growth). Then within a couple of weeks they started to have tissue degradation and have since lost one, I think. I checked everything: lighting (bulbs 6month old), Flow (OK), H20 parameters OK), and then I noticed my RO water ppm were 6-7. I have always been under the impression anything under 10ppm was ok. I ordered all new membranes including the TMD (sp) the real expensive one. (I have a 50gpd unit). I changed out the filters and the TDS meter read 0ppm. So, I did a 35g water change on the 125g and again a week later. I have a noticeable change for the better since. Not all the way healed, but they are looking much better. And to answer your question, I last changed out all the filter about 6 months ago. My advise and what I'm going to do from now on is check the TDS meter and never let it get above 0ppm. Hope this helped! Shawn __________________ Shawn M. Current Tank Info: 125G SPS, Aqualight Pro 3 X 250w MH 4 X 96w Actinic, 1/3HP, Blue Line 55 & Blue Line 20, Phosban 150, 18w Turbo Twist UV, RS 180, (1) Tunze 6045, MP40W

09/17/2009, 03:15 PM	#3
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	Thanks rolodex for sharing. I just hooked up an inline TDS monitor to check weekly with other water parameters. Hopefully, my SPS will come back now. __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/18/2009, 09:12 AM	#5
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	Yes, that was the impression I was under too. Which begs the next question... how often do you change your pre-filters? __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/19/2009, 03:22 AM	#6
RandalB Registered Member Join Date: Nov 2003 Location: Cedar Lake, IN Posts: 1,958	Membranes should be good for a minimum of 2 years.. Fish, you have a problem with your system there if you are eating them faster than that... What's the details on your system? Maybe we can run down what the problem is... Also, 127 from Downer's Grove seems way low for your feed water. Are you on a well or being supplied from Lake Michigan? RandalB __________________ Have Membrane, Will Travel... Current Tank Info: 32 Biocube, 30 Half circle, 120 in wall coming soon all reefs

09/17/2009, 09:08 PM	#4
NanoReefWanabe Registered Member Join Date: Oct 2006 Location: Barrie, Ontario, Canada Posts: 6,639	i was under the impression your RO membrane should last indefinately, if the prefilters are maintained properly, and the water pressure and temperature are within specifications...my filmtec75 has been going for over a year now with 0TDS...

09/19/2009, 05:28 AM	#7
kenrooke Registered Member Join Date: Aug 2008 Location: kitchener ont Posts: 15	i change my prefilters every three months as to preserve the life of the membrane which if hooked up to a soft water system could last up to eight years according to the manufacturer.i have also added a deionizer for extra assurance.in addition i have a hand held tds meter to compare from my outline meter.i measured the inline household water at 560 tds.our water in the waterloo region is often called liquid cement.lol .

09/19/2009, 01:14 PM	#9
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	Guys, thanks for the help. It is RODI. Spectra pure unit with sediment pre filter, carbon filter, two RO membranes and DI. Randal B. I was surprised my tap water TDS was that low too. It is Lake Michigan water. I tested with two TDS meters and got the same results. Buckeye... Waste water is 275 ppm. Purfied is 27 ppm after running for about five minutes. This suggests the membrane is not functioning correctly, No? I was not waiting long enough to take the reading when I got 35 ppm. Also, during the ATO part of the units duty... it might be creating water for a minute or so at a time. I should add a timer to make sure it runs in longer intervals... right? Water pressure is 50 psi. __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/19/2009, 01:59 PM	#10
Buckeye Hydro .Registered Member Join Date: Sep 2006 Location: Cincinnati, Ohio Posts: 4,857	Let's back up a little. Its important to check your TDS on an RODI system in THREE locations: Tap: you reported 275 ppm RO: ??? DI: you reported 27 ppm So we know for sure at this point that your DI resin is shot and needs to be replaced. I need the TDS in the RO water to see how your membrane is working. What is the ratio of waste water to purified water? We're talking about volume here. Should be something like a 4:1. So with about 8 identical drinking water glasses lined up in front of the system, and your waste tube in one hand and your DI "out" tube in the other hand, how many glasses do you fill with waste water in the time it takes to fill up one glass with DI water? And you are right - you want the system kicking on less frequently rather than more frequently. There are a number of ways to do this. Russ @ Buckeye Field Supply

09/19/2009, 04:07 PM	#11
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	OK Recap. Tap 127 ppm RO 47 ppm DI 27 ppm (waste water is 275 ppm, but I don't think you need this value) pressure 50 psi waste flow rate 425 ml per min produce flow rate 500 ml per min - WOOPS! __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/19/2009, 08:09 PM	#12
Buckeye Hydro .Registered Member Join Date: Sep 2006 Location: Cincinnati, Ohio Posts: 4,857	AH-HA! So its likely that the membrane isn't fully seated, or the RO membrane housing has an internal crack/chip allowing waste water to flow out of the permeate port. Pull the membrane out and check the condition of the o-rings on the far end of the stem. Shine a flashlight in the housing and check the condition of the cup into which to membrane seats. Russ @ Buckeye Field Supply Russ

09/21/2009, 09:56 PM	#13
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	SO... I put in two new membranes. For testing purposes, the DI is not hooked up. First run I got this. Tap 127 ppm RO 15 ppm pressure 50 psi waste flow rate 425 ml per min produce flow rate 500 ml per min - WOOPS! This is still bad. So. I figured it must the the resistor tube. Sure enough. This was too long and also slightly corroded. Per the table, I cut it down to 1 inch, then 3/4 inch and still the best ratio or waste to product I could get was about 2.5/1. So. I tossed the resistor tube in the trash and used a JG gate valve instead... dialing the resistance up until the desired 4 to 1 ratio was achieved. Final run. Tap 127 ppm RO 10 ppm - rejection rate is about 92%. Not that great... but I will live with it. pressure 40 psi (lower now) waste flow rate 1300 ml per min produce flow rate 320 ml per min - about 120 gallons per day. This is what I would expect with 40 psi. ratio = 4 to 1 = good So, final assessment is that my restrictor tube was too long and or clogged, this is probably what trashed my RO membranes so quickly. Next, I have to wonder if the test runs I did today ruined my brand new membranes? Also, should I plan to use my gatevalve to control resistance from now on? Any downside to that? I have redone the plumbing so I can easily check waste to product flow rates as part of routine monitoring. Wow. More than I had bargained for! __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/21/2009, 10:45 PM	#14
rbnice1 Moved On Join Date: May 2008 Location: Cedar Hill Posts: 3,905	Can you post some pics showing how you have redone it to check your ratio easier? I mean did you put something inline that allows you to measure both?

09/21/2009, 11:59 PM	#15
Toddrtrex Registered Member Join Date: Feb 2004 Location: Carol Stream, IL Posts: 23,162	Do you know what RO membrane you have? On average they are going to be rated for 90% rejection rate, or 96-98% rejection rate. I have a Dow FilmTec 75 GPD membrane and last time I checked (( about a month ago )) I was getting 97% rejection rate from it. For reference, my tap's TDS is about 150, I am in Lombard, near 88 and 355 so not that far from you. But, there seems to be a bit more sediment in my water, after 3-4 months my pressure goes from around 60 PSI down to 50, so I change my pre-filter more often. After DI, I end up with 0 TDS. My RO membrane is about 2 years old. __________________ Click my name and then "visit toddrtrex's homepage" for tank pictures Current Tank Info: 210g reef and 65g reef

09/21/2009, 11:59 PM	#16
Tadashi Premium Member Join Date: Feb 2000 Location: Ft. Hood, TX, USA Posts: 2,252	Mine would last about 18-24 mo before resulting in 2-3 ppm TDS water. I installed two sediment filters on my system one at 1 micron and then .5 micros, and a carbon at .5. I changed out my sediments every 6 mo since they were so cheap. Carbon out every 8-12 mo. my pressure was at 80 psi. I did not measure between chambers but this would probably have saved me some change outs. __________________ Honey, put down the bleach and step away from the tank. I promise we will spend more quality time together. Current Tank Info: 14-gal Oceanic BioCube (see homepage link for current status)

09/22/2009, 03:18 AM	#17
Buckeye Hydro .Registered Member Join Date: Sep 2006 Location: Cincinnati, Ohio Posts: 4,857	FishTruck - I don't remember - are your membranes plumbed in series - i.e. waste from the first feeding the second membrane, with only one restrictor found after the second membrane? Assuming the answer is yes, and with two 75 gpd membranes, you functionally have a single 150 gpd membrane. I would not use that ball vlave as your restrictor long-term, but rather get a capillary flow restrictor designed for a 150 gpd membrane. They are very inexpensive. Its very unlikely that you damaged the membranes much with your test runs. The buildup of scale in the membranes takes some time. If you only have 40 psi at the input of the first membrane, you probably only have 32 psi at the input to the second membrane - not enough. You have some options to address that if you'd like. Russ

09/22/2009, 08:28 AM	#18
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	Final product after DI is 0 ppm. I was just about out of fresh water. rb nice - I just put a T and some shut off valves at the RO output and RO waste - so I can divert the flow of both into buckets to measure flow rates... without disconnecting anything. Until I get a new $3.99 capillary tube, I am using a gate valve to control resistance. I use these for my calcium reactor to control flow and was luckly late last night to have one lying around. Todd RX - I have two 150 gpd 98% rejection rate RO membranes from Bulk Reef supply. I replaced two DOW filmtec 150 gpd 98% membranes. I was hoping for a better rejection rate than 92%. Maybe they need to run longer? They were getting better with each test. I was just in your neck of the woods at Tropiqautics the other day. Tadashi - the schedule you use is about what I was assuming I would use. Buckeye - my membranes are plumbed in series as you have described. I have two 150 gpd membranes. Will get a new capillary tube. I guess with borderline pressure... I might be better off with a booster. Would this improve the rejection rate? I set the ATO to a timer to fill my resevoir only overnight, hopefully in one long run, to avoid rapid on / off cycling. __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/22/2009, 06:09 PM	#19
Buckeye Hydro .Registered Member Join Date: Sep 2006 Location: Cincinnati, Ohio Posts: 4,857	You won't have luck using an Aquatec 8800 booster pump to drive the two 150 gpd membranes. You could experiment with some of the other brands, but be careful what you buy if you stray into the low cost imports. Rejection rates improve with higher pressure. Russ

09/23/2009, 05:24 AM	#20
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	OK, I am really learning a lot here. Let's say I keep burning through my DI resin more quickly than I want.... but, I also want the ability to make at least 100 gpd (in a pinch). Would I do better with a booster and two 75 gpd membranes, or, to try and find a booster that would work with two 150 gpd membranes. Or, another way to ask the same question... what is the technical issue with boosters and two 150 gpd membranes versus two 75 gpd membranes? I notice that most systems sold with boosters have only single membranes. __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

09/23/2009, 06:29 AM	#21
Buckeye Hydro .Registered Member Join Date: Sep 2006 Location: Cincinnati, Ohio Posts: 4,857	Aquatec 8800 booster pumps are good only up to 120 gpd, assuming a 20% recovery (4:1 wate to permeate ratio). If all you need is 100 gpd, go with a single 75 gpd membrane with pressure boosted to 90 psi. With 65 degree F water, you'll produce about 115 gpd, with a high rejection rate. Russ

09/23/2009, 06:30 AM	#22
Buckeye Hydro .Registered Member Join Date: Sep 2006 Location: Cincinnati, Ohio Posts: 4,857	Fish - just noticed your "Department of Redundancy Department." What a hoot!

09/23/2009, 10:39 AM	#23
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	Thanks! I will see how these membranes do... and if I keep burning through DI resin, go with a single 75 gpd and a booster. __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs

10/07/2009, 07:36 PM	#25
FishTruck Premium Member Join Date: Jul 2007 Location: Downers Grove, IL Posts: 805	OK. Follow up. I swapped my two 150 gpd membranes for a single 75 gpd and added a booster, bringing the pressure up to 80 psi. Also, carefully adjusted until my waste to RO ratio was just exactly 4 to 1. Now, my RO output is 0 ppm. WOW! DI resin should last a little longer now! __________________ Department of Redundancy Department. Current Tank Info: Established 2009 - 300 gal acrylic mostly sps, radion LEDs