Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
pH is not a stand alone value.
pH is controlled by the minerals and salts in the water.
Check the GH, KH, TDS (if you have a meter) and let us know.
Very basically (pun intended!) carbonates act as a buffer, controlling the pH.
If the carbonates are high the pH is most likely to be high and difficult to change.
If the carbonates are low the pH may be low, but is controlled by other things in the water, and is easier to change.
So you do not change the pH directly, you control the minerals, starting with the carbonates.
What kind of fish you you want to keep?
Get started on the fishless cycle while you are trying to work out other things.