DI filter not working

[acrav87]

So i bought a Kent Maxxima hi-s 60gpd ro/di filter off craigslist.
i added a tds meter, and the water coming in from my tap is about 140 ppm
but after it comes out through the brand new hi-s di filter it is still coming out at 30 and 80, i also replaced the sediment filter and carbon filter, i replaced all tubing with new tubes.
also i tested my tds at the pet store, it works fine.

i have dissassembled and cleaned everything, i even switched up some of the filter cannister caps, in case the one on the di was bad, still same problem

i took it to my pet store, he runs the same fro/di filter, so we swapped out his di filter with mine, cannister and all, and mine works fine on his unit, and his does not work on mine, so i know the di filter and the canister and all are good.

i cant understand what the problem could be especially after cleaning and replacing everything except the ro membrane.
i understand i should change that as well, but if this whole unit is shot i dont want to to put any more money into it. my thought is, even if the ro membrane is shot, the di(final stage) should still purify the water, it would just get overworked quicker.

any help, much appreciated

 

[Dr Colliebreath]

I have a similar problem but on a much smaller scale in that the water comes out of my ro membrane at 1 ppm, goes through the first di cartridge (new) and comes out at 4-7 ppm, and then goes through the second di cartridge and comes out at 0. Somehow, tds are showing up as a result of the first di cartridge and I have checked the results with 3 different meters.

I changed out all of my filters, membrane and resins and still have this. I also changed out some of the tubing, including between the membrane and first di. I have concluded that the housings must have soaked up some tds and am going to soak them in a dilute bleach solution (say a half cup of bleach per housing) for 12 hours and then in an acid solution (muriatic acid at 1:10) for another 12 hours and then in rodi water that I change frequently for another 24 hours. That hopefully will solve the problem. You might try the same for each of your housings and the membrane housing. The whole unit shouldn't be shot.

Good luck.

 

[acrav87]

im presently soaking everything in white vinegar and water, and hopefully that will work, but thats the last option ive come to, i chose not to use bleach because any trace elements of chlorine overwork the filters substantially, or so ive read

but even if i only run the water straight from the tap to the di, it goes in at 140ppm and comes out in the 30's basically with every trial and error setup ive tried the best i can get is 30ppm

also when i first put the new filters in, i ran everything for an hour and a half to get rid of any possible dust particles and such, still no luck, let me know how your turns out, ill do the same

 

[Dr Colliebreath]

You really need to change out your membrane to know. If you get the same tds out of your di from tapwater as you do the membrane, it sounds like the membrane is shot. Good luck.

 

[Ron Reefman]

If your tap water is only 140tds and you are getting 30-80tds out of your RO/DI, either your RO membrane is shot (you did get it off Craigslist, I don't care what the seller said about how new it was). Or the DI resin is more than dead (which wouldn't raise the tds from the RO), it contaminated and adding tds to the RO water. Try checking the tds after the RO membrane and before the DI resin. If it's down in the single digits, it's the resin (but I have serious doubts that it's the resin).

I'd just get a new membrane and new DI resin and try again. But then you should have planned on that from the start given you were buying a used system off Craigslist.