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Old 10/07/2017, 08:03 PM   #7
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moze229's Avatar
Join Date: Oct 2002
Location: Triangle Area, NC
Posts: 698
Originally Posted by outssider View Post
your ro membrane does most of the work as far as tds. I'd be looking there for problems. water could be bypassing the membrane without leaking out the housing.
I was able to pull apart the canister for the membrane tonight and can verify something isn't right. There's barely any water being led to the waste line. It's like a 2% rejection rate instead of 98%. The membrane itself seemed dry. The water is definitely bypassing the membrane somehow, but I'm not sure how. When I pulled it out it was seated firmly and gave a nice suction sound when I pulled it out, so I think it's sealed well. The seal around the membrane seems in order and fits nice and tight, and the o-rings at the bottom are not damaged. What else can I do?

The only thing I can think if is this. Originally since day one I've used the Dow Filmtec BW30-1812-75 membrane but they phased that part and replaced it with BW60-1812-75. This is the one that I'm currently using. The only physical difference that I see is the length of the membrane on the sleeve. This one is slightly shorter.

My gauge reads ~60 PSI. I don't think pressure is a problem, it never was before. I'll also admit that the accuracy of this pressure gauge is likely an estimate at best, but it's always read the same. Bad membrane perhaps? How can I check without just buying another one? Now that I've done further research on this model, it seems that some are having issues with higher TDS readings. I've yet to find a claim that they are having a bypass issue.

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Current Tank Info: 24 Aquapod w/120w LED Bridgelux 55 X 3 - Softies and LPS
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