any aquarists here? I need some help...

[Bolisnide]

hiya,
So, my water seems to be right on now... 0 ammonia, 0 nitrite, and nitrates at what appear to be a 10.
My son is itching for something exciting in the tank, and I was kinda thinking maybe a beautiful male betta may be a good choice.
What do y'all think?
Only problem may be that my water is hard, and my PH tends to be on the higher side (today tested at 7.5, I can't figure why, unless water quality can change the pH.)?
Many thanks

[Bolisnide]

or... an African dwarf frog? my kiddo's other choice..