Good info from RD.
All I'm going to add is that the low pH could be indicative of another issue such as depletion of KH (carbonate hardness) caused by your beneficial bacteria processing Ammonia and Nitrites. I'd check those and your KH.
I use a small amount of Seachem Reef Buffer with each water change (50% weekly) to keep my KH up in my 75g Flowerhorn tank.
Another great article on how all those water parameters interact:
http://www.americanaquariumproducts.com/AquariumKH.html
All I'm going to add is that the low pH could be indicative of another issue such as depletion of KH (carbonate hardness) caused by your beneficial bacteria processing Ammonia and Nitrites. I'd check those and your KH.
I use a small amount of Seachem Reef Buffer with each water change (50% weekly) to keep my KH up in my 75g Flowerhorn tank.
Another great article on how all those water parameters interact:
http://www.americanaquariumproducts.com/AquariumKH.html
