Anyone use 1:1 membrane? Mine is failing prematurely

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rajdude

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Ok so last year, I got a RO-DI filter from Pure Water Products. Membrane is their Pentair GRO-50, which is a 1:1 water-waste ratio membrane.


Everything was worked fine for about a year. Then the water production dropped. I diagnosed that the membrane was not producing water, it was only a drip drip. Pure Water Products sent me a free replacement membrane (which was nice of them). That worked for 10 days and back to drip drip. It measures to around 40 ml per minute. It should be around 150 ml per minute.

Have been troubleshooting for a days now, already checked the water pressure, flow, temps, etc. All is well. I have even dismantled the unit and individually checked the parts. No blockage. Drain water is measuring around 180 ml / min. Has a 150 ml flow restrictor....which is what Pentair recommends for this particular membrane. I am probably producing-using 20 gallons per day or less. I am on city water, 175 TDS input. Fairfax, VA, known to have chloramines. TDS for output is 1-3. Output after DI is 0

I am at the end of troubleshooting with Joe from Pure Water Products (he has been very helpful, BTW)...........but we still do not know what the problem is. I don't want to get a replacement membrane, only to foul it again.

So what I am asking is:

1. Is anyone else using these fancy 1:1 membranes?

2. Am I using too little pre-filtration?
I have one sediment and one chloramine reducing carbon block. Both seem to be ok, judging from the water flow post those two filters.

3. Any suggestions on what I should test next?

Or should I call it a day and go with the usual 1:4 membranes?
 
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rajdude

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Hello everyone,
Newbie here, so please be gentle if this question has been asked here already.....maybe that is why I did not get any answer (I did search before posting).

I really need to do a water change and hence, really need to get the RO-DI filter running again. I have been researching and still cannot find out what approach should I take. I do not want to blindly buy another membrane, because I am pretty sure it will get fouled again.

I have been checking what other vendors do. I see they do have two carbon blocks in series, for those cases where there is a lot of chlorine or chloramines. Now I googled our water in Fairfax and yes the water company does mention that they use both, depending upon the time of the year.


Quote:
Chloramines are normally used July - March, and free chlorine is generally used April - June.

Interestingly, the replacement membrane came in early July, and that is when they add chloramine. Maybe it cannot handle chloramine?

Also, I am not sure if they are using so high levels that my chloraguard carbon filter was overwhelmed....and ended up passing too much chlorine to the membrane......causing its premature death.

Not knowing what else I could do I think
1. I should add another housing and add a second chloraguard filter.
2. Also replace the existing chloraguard filter and also replace the sediment one.
3. Then replace the membrane and see what happens.

Does this make sense?

-Raj
 
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rajdude

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one word....wow!

And thanks a million for posting this. I was unaware of this video......although I have watched lot of BRS' videos.

So I guess the short answer to my own question would be:
Add a second carbon block and test monthly for chlorine-chloramine.
 
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rajdude

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I have an update......a bad one at that!

I have managed to fry my THIRD membrane. I am not sure what is happening.

After researching some more and watching that video above, I decided to make some changes to my RO-DI system
I added another stage of carbon block
Replaced all pre-filters:
new sediment,
new carbon blocks
new membrane.

Still, after about a month, same thing happened.....membrane is not producing anymore.
TDS before 180
TDS after 7
TDS after DI 0

I am producing maybe less than 30 gallons a day.

I am at the end of this rope....not sure what else I can do. Talked to the original vendor multiple times (PureWaterProducts) also talked to BRS, trying to talk to SpectraPure also (no talk, only e-mail....waiting for a response)...........so far no one knows what is going on!

PLEASE HELP!

PS: I am willing to change my membrane to something different.......but will I end up frying that one also?


Details of my RO-DI system:
I have a mix of PureWaterProducts and BRS

This is what I currently have:
Sediment: (1 Micron Premium ROsave.Z Sediment Filter - GE)
Two carbon blocks (BRS' Universal Carbon Block Filter - 1 Micron) Note: I used to have only one carbon block and with that single one, the membrane lasted 9-10 months.
Water pressure gauge
Pentair GRO-50EN 1:1 membrane
150ml drain restrictor (that is what this membrane model needs)
One way valve
Y split:
Housing with Calcite Cartridge for drinking water



Housing with DI cartridge (currently has BRS' DI Resin (Color Changing)) for aquarium water
Three way TDS sensor

This system fills two Brute drums
10 gallon for drinking water
55 gallon for aquarium water
 

mrlavalamp

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Supply pressure?

The pressure you supply to your RO membrane has a large impact on production rates and supplying more pressure often yields better performance with respect to rejection rates.

BRS explains this really well (and shows results):
I would also look into adding a flush line and flushing the membrane for 30 seconds each time you start it up making water for your aquarium.

I really like the DOW and spectrapure membranes. My tap water is ~750 TDS and I get a little over 10 coming out of mine.

If it were my money I would ditch the pentair membrane and switch to standard style RO membrane with housing and flow restrictor with a built in flush valve. Also consider a booster pump depending on what your supply pressure is at.
 
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