RO/DI help

[AllSignsPointToFish]

Something doesn't sound right. With that amount of dissolved CO2, I would've expected the pH to be lower than neutral. If that's not enough CO2 to drop the pH, then CO2 is probably not the issue.

 

[AllSignsPointToFish]

If I did my math correctly, 50 ppm is roughly 50 mg/L. 50 mg is around 8.1 x10^-4 moles of carbonic acid. Since the acid is diprotic and assuming total dissociation (probably some error with this assumption as I was lazy and didn't look up the dissociation constant), the associated hydronium ion concentration is 1.6 x 10^-3 mol/L, yielding a pH of around 2.8. So, essentially, the pH should not be 7 with that concentration.

 

[AllSignsPointToFish]

The actual pH will be higher as not all of the carbonic acid dissociates.

 

[don_chuwish]

Yikes. My tap water is never more than 50ppm TDS. I just can't imagine...

 

[Fishfinder]

Ya just tested with a professional kit water is 6.4ph

 

[Fishfinder]

I'm just doing some follow up, in case this helps any one.

I just added a booster pump to my RODI system. I'm running my RO membrane at 80psi. It is taking my incoming water TDS from 1120 down to 3 after the membrane. My DI is polishing off the 3 TDS and the life of my DI is greatly increased. Prior to the booster pump installation I was getting 60 TDS after the membrane. If anyone is having difficulty getting TDS low I strongly recommend trying a booster pump

 

[Frop]

I'm just doing some follow up, in case this helps any one.

I just added a booster pump to my RODI system. I'm running my RO membrane at 80psi. It is taking my incoming water TDS from 1120 down to 3 after the membrane. My DI is polishing off the 3 TDS and the life of my DI is greatly increased. Prior to the booster pump installation I was getting 60 TDS after the membrane. If anyone is having difficulty getting TDS low I strongly recommend trying a booster pump

Wow! That's nice! I think my current problem is water temp. I run mine at 100psi too but my water is warm.