I would look around for another heater. I use the Marineland Stealth visitherm. Its a very good brand that was reccommended to me. It may be a little more expensive but worth it. Also, you don't want to mess with your ph.7.2 is fine.Its better to be a little high or low than to have fluctuating ph because thats worse for your betta than a ph that is a little high or low. Hope this helps.