RODI
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Randy Holmes-Farley
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Sorry, didn't have time to study every post in this thread carefully, but have you verified that a brand new RO membrane gets an appropriate rejection rate on the TDS and that the explanation for rapid DI depletion is not just CO2 getting through? I didn't see that sort of discussion after someone initially asked about new membrane function.
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jtl
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A new membrane works great but as it gets older it loses its effectiveness and consequently I use DI very fast to maintain 0 tds, I am not sure what your reference to CO2 is all about so I cannot speak to that. I am going to try a different restrictor and see if I can force more water thru the membrane. The interesting thing is these systems are mostly bullet proof if you just use a quality membrane and the proper pre-filters.
JoshH
Tank Status: Wet...ish, growing things....
The CO2 reference is what we were referring to when we asked about city or well water. Pre filters do not remove CO2 from the water and it chews through DI. Having CO2 in your water from the city is pretty rare but very common in well water. Using a different flow restrictor will actually force less water through the membrane and not more. Having a 1:4 product to waste ratio helps keep build up from forming on the outside of the membrane and prematurely clogging it.
Randy Holmes-Farley
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CO2 in source water (usually wells) easily gets through an RO and rapidly depletes a DI. It is a big problem for many folks.
https://www.aquaticlife.com/blog/how-co2-can-impact-di-resin-consumption/
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jtl
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Makes sense. I don't have well water
That is the plan but I am afraid that this membrane may already be shot.
Fin
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You might also try try collecting your RO water (with DI disconnected). Aerate the RO water with an air pump and air stone overnight and then run it through the DI resin separately.
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jtl
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JoshH
Tank Status: Wet...ish, growing things....
Is there a slight gap between the bottom of the casing cap and the actual body? If so, to me, this points directly to an improperly seated membrane. When inserted all the way the cap should screw ALLL the way to the bottom of the threads. You would be surprised as to how much force you need to push the membrane all the way in to it's seat.
JoshH
Tank Status: Wet...ish, growing things....
That and a 1:2 product to waste ratio seem to be your only issues, realistically if your membrane works excellent at the beginning then deteriorates over time it's more than likely the low waste flow that's your issue. But ensuring the membrane is properly seated is important as well.
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jtl
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I will double check the seating but I am certain that it is in all of the way. I have a new restrictor ordered but I suppose nothing will change if the membrane is ruined.
Forsaken77
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Chlorine/chloramine would be the only thing that destroys a membrane, correct? Assuming you're not running scolding hot water through it, lol.
My thought was maybe the carbon was exhausted.
Randy Holmes-Farley
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yes, aside from things that shouldn't be in drinking water.
Is there a slight gap between the bottom of the casing cap and the actual body? If so, to me, this points directly to an improperly seated membrane. When inserted all the way the cap should screw ALLL the way to the bottom of the threads. You would be surprised as to how much force you need to push the membrane all the way in to it's seat.
This "gap" varies by brand of RO membrane housing. If the lid wasn't screwed on far enough, then it would leak at the oring
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jtl
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Hi Russ,
You folks tried to help me on two occasions with no success so I see no reason to go for three and waste your time. The last time we spoke I replaced the membrane housing on the chance it may have a hairline crack. I reseated the membrane, we talked about pressure and temperature. In the end the only thing that works is to replace the membrane to save on DI and that gets to be about a toss up in cost. I was surprised that I tried two different capillary restrictors and neither one worked any better than my regulary 550 inline restrictor. I guess the good news is that I only use about 75 gallons of RODI per month
