RO/DI Membrane, When to change????

Z

Zoa_joc

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Hey Dfwmas,

I have a 5 stage Ro/DI ( BRS) I use maybe 25g a week tops. My DI fails around 6-8 weeks well turns brown. I have changed all my pre filters and new resin. Day one tds going to the DI was ( 3) few days later (5) with all new filters , I am at five now as I do a water change a few days later i see a red film on my glass so I do another 20% same if not worst.The unit is 13m old is it time for a new membrane? also lmk how often you guys and gals change pre filters and membranes, thanks in advance ......
 
Do you have a TDS meter? The membrane deteriorates over time, and one of two things happens:

1) output declines sharply or ceases completely
2) TDS level rises much higher than previously, using up DI resin more rapidly.

Membranes are rated 1-5 years because water quality varies so greatly from county to county. I can use a membrane for years, but others have to change them out sooner because they have different (municipal or well) water.

The red film on the glass -- that's in your aquarium? You may have cyano bacteria breeding/blooming. Changing water doesn't kill it - they aren't related like that. You can get rid of cyano three different ways: http://www.reefaddicts.com/content.php/42-Cyanobacteria-what-is-it-and-how-can-I-get-rid-of-it
 
Just the guy I was lookin for! yes , the tds is reading 5 atm before the resin and its not cyano. I ran two treatments for that back to back and it did not budge. I have two fish in about 80gals of water and only feed once a day. I have to much $$$$ invested so I already ordered a new membrane. if this helps, the same stuff that was on my sediment filter is the same stuff that will grow on the wall and it laughs at chemeclean at 2x the dose. and i have a 30g fuge with tons of macro on a 60g and oversize skimmer. my sps are loving it along with the chalices just the zoas are hurting
 
I'm wondering if you have the filters installed in the wrong order? The first filter is the sediment filter, which is pure white. Then carbon, which looks like it has a plastic woven net around it, then another carbon, then up to the membrane housing on top, and then finally to the DI resin - which if inverted and unscrewed will look like blue and gold glass beads.

If the TDS is 5 before the DI resin stage, DI should last much longer than 6-8 weeks. If you are installing it in the first stage, it will quickly change color and be consumed.
 
this is my configuration..... Purtrex 5 Micron Sediment Filter,MATRIKX CTO 5 Micron Carbon Block,MATRIKX CTO 0.6 Micron Carbon Block .... I flushed the membrane for over an hour last night now my tds is a (3) before the d/I now. I have a Dow Membrane , I think it has one of the best dissolved nutrients rejection rate like 98%????

all these filters are 4 days old

I am thinking that the color changing resins life is a lot less the the reg?
I am in a commercial building my pressure on the system runs about 62-71 psi a lil higher than most I would think?
 
For the most part, it sounds like everything is working as it should, and your TDS numbers are excellent. I don't see why the DI would be spent so quickly if the TDS is 3. Those should last you 6 months or more. Color-changing resin shouldn't degrade lifespan-duration.

Do you have this RO system connected to a sump with a float valve that turns on and off multiple times a day? Perhaps you're suffering from TDS creep?
 
What is your tds from the tap. Comparing that to your tds after the membrane is an easy way to tell if it is doing its job. I make probably 10gal a week and my membrane lasts for 3 or 4 years.
 
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