My pH level is 6.4 when the lights and CO2 are on, the pH is 7.4 when I test it early morning when the lights are still out. I also have an airstone connected to an airpump running at night when the lights are out for some O2 for the fish.

If I put peat in my canister filter,will this give my water a steady low pH even at night ? Should I use Seachem's acid buffer?