kennyman

I am using Acid Buffer for one of my tanks to convert excess KH into useable CO2. It the resulting ph bounce safe for a planted tank that contians fish?

BryceM

This kind of thing will give you a one-time shot of CO2, similar to dumping in carbonated water. Adding acid and carbonate together will produce CO2:

H+ + HCO3- ----> H2O + CO2

The problem is that the other dissolved solids in the buffer solution remain and you drop your KH as bicarbonate is consumed:

NaHCO3 + HCl -----> Na+ + Cl- + H2O + CO2

If you do this frequently, you'll build up sulfate, chloride, phosphates, or whatever other thing is in your particular acid and buffer. You'll accumulate sodium if you add sodium bicarbonate or calcium if you add calcium carbonate, chloride if you add hydrochloric acid etc. Also, the resultant pH changes can be dramatic, especially when your KH gets close to zero. This is a disaster waiting to happen.

This is really a very poor way of trying to add CO2. If your tap water has a very high KH, driving it down in this manner adds a ton of undesirable 'stuff' to your water. Any benefit you get from the resultant CO2 is temporary as the CO2 quickly dissipates.

Seachem

I agree in part that this product should not be used to produce CO2 to fulfill the needs of a planted aquarium as this effect is temporary. This is an acid simply used to dissolve KH, nothing more. Regarding your original question, pH fluctuation could effect some fish depending on the severity of the drop. The severity of the fluctuation would ultimately depend on the amount of KH present vs. the amount of Acid Buffer used.