pistorta

What would be the best way to decrease alkalinity (carbonate hardness) to permit the addition of CO2 to affect (by decreasing) the pH. The aquarium utilizes a CO2 controller, but because the buffer is so large and the pH is naturally high ~7.8, I am unable to bring CO2 anywhere near 15 ppm. Any help anyone can offer would be appreciated. I have been toying with the idea of using RO/DI water to fix this but am unsure if this is the best course of action. - FW Planted Tank 120 Gal. Thanks in advance.

pistorta

Anyone want to take a stab at this for me?

Dino

I would go with using the RO/DI water.
Use it to dilute your regular water until you reach the results you desire.

Do this slowly, over several waterchanges, so as to not harm the fish.