Nitrate in my RODI

mdrReefer · Sep 16, 2022

HI Folks,
My ATI ICP came back showing 2ppm nitrate in my RODI water. I have a mixed bed resin followed by Spectrapure Silica buster. Both are only 2 months old, as are the sed and carb filters. I estimate about 300 gal made with them so far. System = Sed, 1mc Carb, 1mc carb, 2 RO 100GPH, Mixed Bed, Silica Buster. Just curious how to deal with this? I assume that I should go to a separate Anion, Cation canister and finish with the silica buster. I am also assuming that its my water supply this is coming in on. Just surprised with such a new mixed bed that is only about 1/3 color changed so far. Any thoughts of those knowledgeable on the subject would be appreciated.

vetteguy53081 · Sep 16, 2022

mdrReefer said:
HI Folks,
My ATI ICP came back showing 2ppm nitrate in my RODI water. I have a mixed bed resin followed by Spectrapure Silica buster. Both are only 2 months old, as are the sed and carb filters. I estimate about 300 gal made with them so far. System = Sed, 1mc Carb, 1mc carb, 2 RO 100GPH, Mixed Bed, Silica Buster. Just curious how to deal with this? I assume that I should go to a separate Anion, Cation canister and finish with the silica buster. I am also assuming that its my water supply this is coming in on. Just surprised with such a new mixed bed that is only about 1/3 color changed so far. Any thoughts of those knowledgeable on the subject would be appreciated.

Look at your water source going into RO unit and what is age of cartridges as well as membrane?

Randy Holmes-Farley · Sep 17, 2022

I expect it is not accurate for nitrate in the ro/di effluent unless the di depleted.

mdrReefer · Sep 17, 2022

vetteguy53081 said:
Look at your water source going into RO unit and what is age of cartridges as well as membrane?

The water source I don’t have any details on beyond is 240tds. The RO membrains are 1 year old and 6 month old. In researching this some else suggested the anion resin is depleted, which might be the non color changing part of the mixed bed. You think perhaps the RO membrane? My TDS is between 0-3 (two meters) coming out of RO and 0 after DI.

vetteguy53081 · Sep 17, 2022

mdrReefer said:
The water source I don’t have any details on beyond is 240tds. The RO membrains are 1 year old and 6 month old. In researching this some else suggested the anion resin is depleted, which might be the non color changing part of the mixed bed. You think perhaps the RO membrane? My TDS is between 0-3 (two meters) coming out of RO and 0 after DI.

This is all pointing to water and cartridges/resin in need of change

mdrReefer · Sep 17, 2022

vetteguy53081 said:
Look at your water source going into RO unit and what is age of cartridges as well as membrane?

I pulled my first mixed bed di. It looked about half depleted. I went ahead and replaced that. I’m also going to go from two cheaper brand 100gpd ro membranes to two Dow 75gpd membranes to help reduce the DI consumption. In addition I’m going to go to 3 di chambers with separate anion, cation, and a final silica buster. That way I can’t get fooled by anything that is depleting the anion side of the mixed bed.