No one mentioned anything about oxygen exchange in the aquarium? which is a good reason for a drop in ph
? Like the more CO2
that is allowed because of lack of oxygen, the ph
would drop to 6.0 at least. This is not uncommon. I have heard opening wondows and whatnot for a little while, has even helped tanks increase ph
. What kind of surface tension do you have?.. Glass tops? Aeration? etc...
I have heard countless problem storys about glass tops and ph