I have a 30 gallon fish tank with discus fish I can't seem to lower the PH to the correct setting. I have tried everything at the local pet store it is about 7.5 I need 7.0 please help:confused:

What is the ph of your tap water, is it 7.5?
Or, is your tanks water 7.5 after using the ph down solutions?

Do this, fill a glass with tap water, wait about 30 minutes and check the ph, then post that here.

There's a product at your LFS (local fish store) called bullseye. It restores ph to 7.0. Just follow the directions on the bottle. I have used it successfully in my tanks.