How To Raise Ph Level

[jordan1231]

I was wondering how to raise the PH level to 8.0 if it is at 7.0 now? I thikn my molies are doing good because of my low PH. I had put a 7.0 PH tablet in the water ( a pet store told me to) but the more I am reading on Mollies is that they like a harder PH. I already put aquaruim salt in but it did nothing to the PH.
ANy help?
Thanks