Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
pH is not a stand alone value.
The minerals and salts in the water are controlling the pH.
Most often the KH is fairly high, and this keeps the pH high. Not always, I have seen posts about some really odd water!
Anyway, test the GH, KH and pH in the tank and post back, and test the tap water pH, GH and KH right out of the tap, then repeat the pH test on some water that has sat out 24-48 hours.
Why do you want a lower pH?
If it is for certain fish, go by the GH, not the pH.