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Group: Forum Members
Last Login: 11/17/2009 10:33:37 PM
Posts: 231,
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| Is there a good way to tell when the RO membranes in a RO/DI system really need to be replaced? I typically ignore my RO/DI system until the TDS numbers begin to rise. Then, I replace the sediment filter if it looks dirty, the carbon block filter for good measure, and the DI membranes if they've changed color enough. I then flush the RO membranes (if I haven't in awhile) and check my new TDS numbers. If they're low I figure I'm good to go. What I haven't been doing is periodically checking good water to waste water percentages or anything like that... always figured input water temperature fluctuations would make that meaningless. Manufacturer says the RO membranes "typically" last 3-5 years... as if that's helpful. So. replace the RO membranes when I can't get the TDS numbers to stay down? Or is there more to it than that? Thanks, - Mark
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Group: Moderators
Last Login: Today @ 3:03:07 PM
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You should try to track how much water you can process before needing to replace the DI cartridge to keep the TDS low. As the membrane goes bad, one of two things should happen. Either it should permit more stuff to get past, but the DI cartridge will kick in and drop the TDS level at the expense of going through a lot of DI resin. Or, the membrane will clog and production should drop off.
Steven Pro, yeah that is my real name.
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Group: Moderators
Last Login: 11/19/2009 1:09:50 PM
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| it does vary of course pending source water quality and maintenance and mindfulness of unit (avoiding use during heavy sediment times like after storms, line flushing... temps through membrane, tending to prefilter frequently, etc.) In general though... the carbon is only good for a couple months... the prefiler similar (if using only a 5 micron or more coarse, please consider adding a second stage mechanical 1 micron filter to extend the life of your membrane). IMO its uncommon for RO membranes to go much over 2 years. That is to say... if you water is bad enough to want to use an RO, you likely will be closer to 3 than 5 years. I would not be surprised if the 3-5 year membrane lifespan was asessed by the average of people using RO units for drinking water and not by reef keepers  Many folks with reasonably good tap water still choose to run RO for taste/quality of human consumption. They have a higher standard. But the majority (IMO) of aquarists seeking RO water have lower quality tap water (hence less lifespan to the membrane) than the drinking water folks. And that drives them to buy an RO unit.
. Anthony Calfo
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