Having hard water does not necessarily mean that you have a high PH. I would get a GH/KH test kit and also a PH test kit just to be on the safe side.
Even if you're PH is a bit high, I wouldn't stress about it unless there is a problem with you're fish. You're much better having consistent water chemistry then messing around with trying to raise or lower you're PH to some idealized "number" (in my humble opinion of course).
My betta lives fine in relatively hard water/high PH. But I would definitely get a test kit just to make sure you're not off the charts.
Here is a link explaining GH, KH, and PH