Matt, my tank is a 75 gal RR. The pH controller shows 8.2, effluent pH is 6.6, effluent dkh is above 20 using Salifert low res (full 1 ml syringe with an additional .2 on a new syringe) or 21 drops using a Red Sea test kit, which equates to 11 if I remember right. Do you still think I should reduce the CO2 entering the reactor?

I have had this setup for four days now and I can see a difference in raising dkh and pH. I check the pH controller a couple of times a day and the range is reducing.

Thanks for your help.