7.0 is fine, slightly acidic ie 6.6-6.8 is ideal. But bettas will thrive in a wide spectrum of pH levels so the worst thing you can do is monkey around with pH up, pH down and the like. Whatever pH your water is will be just fine as long as it's constant.

 

ok good because mine seems to always sit at 7.5

 

Test it every couple of days and use ph down if it's too high.

 

I agree with Kelly. Fluctuating ph levels are not good for fish.