001 ppm even after filter change?!?!

Yep, still 0 tds.

I guess there was such a small leak through that o-ring that 17 tds from the membrane was mixing inconsistently with 0 tds from the di at a ratio enough to dilute it to 1tds. But, as it was not leaking consistently , that's why some tests I was getting 0 and some tests I was getting a tds reading of 1.

All this headache from such a small 0-ring.. I was about to throw out my tds meter, if not for the fact that I still had some known 0 tds water that consistently read 0.


And thank you to everyone for all your ideas! Much appreciated!


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Remember, prefilters and carbon blocks have very little to absolutely nothing to do with final TDS, their sole purpose is to protect the RO membrane from TSS, suspended solids, big stuff not measured with a TDS, dissolved solids , meter. The RO removes 90 to 98% of the TDS and the DI gets the rest. Dissolved solids are 0.0001 microns, suspended solids are more like 1.0 microns and larger, 1000 times bigger than dissolved solids. You can change all the prefilters and carbons you want and they have little if any effect on TDS.

Also make sure the DI resin is packed tightly with no space as DI actually shrinks slightly with use.

Your RO only TDS coule be better, my tap TDS is over 650 and my RO only TDS is in the 3-4 range. A little known rule of thumb says for every 2% you increase your membrane efficiency you double the life of your DI resin. My rejection rate averages 99.35% so DI lasts a long long time. A new membrane would be cheaper than just 3 or 4 DI replacements and pay for itself quickly.

 

Thanks for all that info.

I'm getting about 200 gallons out of the system as-is before di needs to be replaced. And I do understand the purpose of the sediment and carbon, but I change out all three at the same time no matter what.

Do you think 200 gallons before di change is unacceptable? Should that be higher, depending on the numbers I gave? I know the membrane isn't doing the best, but Its doing an acceptable job, or so I was thinking?!?


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I've put well over 400 gallons through mine, and my DI is still doing its job. It will need to be replaced within the next 100 gallons or so (starting to change color...about 1/3 up right now). My starting TDS is 193. My TDS after the membrane is 002.

 

Well then, I've learned something new. Your tds is almost 200 less than mine going in, however, the 2-3 coming out of ro is consistent with azdesertrat. Guess I will be replacing my membrane next filter change with the rest of them.


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Should I get a spectrapure membrane for my brs ro/di system?


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I would, they are the only company who treats, tests and ships their membranes wetted in a special solution to improve their performance. The select series is only like $10 more and is guaranteed in writing.

You are actually doing good at 200 gallons with that RO TDS, my old Typhoon III used to get 13-15 TDS out of the RO only and I got almost exactly 150 gallons per fresh DI no matter where I bought the resin until I tried Spectrapure. My cost of ownership is way down now as I get over 1000 gallons per DI cartridge or about 7 or 8 times the water per cartridge.