RO membrane from 4 TDS to 24 TDS in 1 week

HM3105

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Hi,

I have your 99% rejection membrane and it was working great. I use it about once a week and have had it for about 3-4 months. When I started my RO unit this week the TDS coming out of the membrane after 30 minutes of running was still 24 TDS. I ran it a few more hours but it never changed. The inbound TDS was ~200 which is fairly typical.

I don't really know whats causing this but its happened several times with other membranes from other vendors. I thought it was just cheaper membranes I bought from other vendors but when it happened on this membrane I thought maybe it was time to ask for help.

I use a smart buddy RO booster pump to regulate the pressure.


TLDR: membranes work fine for a few months then end up with 90% or less rejection rate.
 
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HM3105

HM3105

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What kind of source water are you using? Have you checked for chlorine and chloramine? They can mess up the RO membrane and reduce it's ability to reject dissolved solids
Well I've heard off and on chloramines but if it were that wouldn't the TDS slowly move up vs. jumping all of the sudden from one week to the next ? It went from 3 TDS last week to 24 this week. That's what's confusing me.
 
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HM3105

HM3105

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I would think so also but can't really think of anything else if it's only a few months old. You're measuring after the RO before the DI?
Yep, I have one of those 3 probe digital testers. It measures inlet (200-240), after membrane (3 a week ago, 24 last night) and after DI (0). I thought the probe might be bad or have a bubble struck on the probe but it exhausted half a DI cartridge running it for 6 hours.
 

Do you have a frag tank, frag rack or some other place for coral frags currently?

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