001 ppm even after filter change?!?!

Changed the filters in my ro/di a month or so ago, tested water. 0 tds. Made about 200ish gallons of water if not more and tds meter finally started showing 1. Changed all filters except membrane again . Water is reading 17 ppm after membrane and before di. After di it is reading 1? Can anyone tell me what may be wrong? Im using a handheld hm meter. Tested it on known 0 tds water from my last batch and it shows 0. Test water from ro/di again and it shows 1!!

Tds from tap is about 490ish if I remember correctly.


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Not sure how to help but i know .01 tds will not hurt you any..

 

Yea, that may be true, although I have also heard anything other than 0 is unacceptable. The main concern of mine is that after a filter change it should be at 0 like the last time I changed them. I can't understand how this time could be any different.


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yeah idk..im sure one of the pros on here will chime in..

 

if 17 tds are coming out the membrain, then its time for it to go

 

It's always had about 12-17 tds out of the membrane. Last I calculated I think it came out to about 97% rejection rate? Which I believe is in spec for the membrane? The thing is, shouldn't the di resin be able to take 17 tds down to zero, and it would just exhaust faster than if the tds was lower from the membrane?


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You're correct; the DI would handle that, just at the expense of a lower life. You did replace the DI as well, correct?

The only other thing I can think of is that all meters have a tolerance and accuracy on their measurements, and handhelds typically tend to be less accuate. So 1 might actually be 0. Also 0 might actually be 1 or 2. Look up the specs for your meter and see.

 

That's what I'm thinking, too. Yes, changed the di also. I let it run for a few more hours and tested and it came back zero. Then let it run a little longer and tested again just to be sure and it came back with 1. Then ran for another hour, tested again and came back zero, let run another hour and tested, came back zero again.. I don't necessarily think the meter is off but maybe it had to rinse a little more and like you said, it might have been somewhere in between 0 and 1 and that's why it was going back and forth?


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IME it can take 5 or so gallons of filtered water to flush a new carbon filter or DI resin b4 getting that 000 reading.
But other then that the only thing i can think of that could be different is your water pressure or a canister that may be leaking.

 

Yea, but I have run over 20 gallons through it now..

BUT

I think I found the problem. Your leak theory kept in my head and with a tds of 001 it was obviously going through di, but not all of it.. So, the leak had to be in the di chamber. I took the di cartridge out and the rubber o ring looked a little too indented from me previously over tightening. I thought this had to be where some water was leaking through giving me 001 tds. I flipped the rubber o-ring on the cartridge over to a new, flat side and tightened the cart. So far, it is now giving me 0 tds. The mystery may be solved. I'm still gonna test it a few more times before I'm sure, but I'll let you know.


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