RO unit and DI resin quesiton

What kind of resin do you use? I've heard BRS resin turns brown well before tds creeps up! I think its more oxidation than anything, which would make sense to me.

 

I'll follow this one, I've often wondered the very same thing.

 

I.have never had a membrane register at zero. Even a brand new one.I didn't think they have a 100% rate. I think I have read that they have a 97% rejecting range.Which is why you use di resin to get to zero. Maybe guage is off slightly.

 

The lowest reading I am getting out of my membrane is around .01/.02 area. This is a good question for BRS however. Have you contacted them to see what their suggestion is. Probably not a bad idea to hang on to the resin until the TDS starts to rise.

 

Well I had to go out and ask BRS and this is what I was told.

On a technical level, half of the DI resin has a pH indicating dye inside of it. As the ions exchange, the pH in the dye changes causing that half of the resin to turn from blue to clear. Because the other resin is brown, it gives the appearence of turning from blue to brown. It's possible for the pH of the water to be such that the color can change without being depleted, but its pretty rare. Most likely circumstance if your cartridge has turned entirely brown is that your getting close to the end.

I then asked: So the color change is just a barometer of the depletion and as long as I am monitoring the TDS then I should be good until they start to rise?

Response: Correct, its the TDS meter that has the ultimate say, but a good bet you want to atleast get an order in for some resin as your likely to need it sooner rather then later


I would have resin on hand and wait for the TDS to begin to rise. I have a Dual DI system so I will just start waiting until the second canister is about 20% depleted before I change. I guess that is one of the drawbacks of having 2 chambers.

 

Which TDS monitor are you using? I am a little confused here. If your meter does not read below 1 how do you know that it is 0 when it leave the RO membrane? Seems to me that there may be an accuracy issue with your meter.