need advice on ph

[MYSTIC78]

hi, I recently received a ph moniter and after calibrating it I installed it and it was reading 7.6 - 7.7 . so I double checked with another test kit and it looked pretty close. my alk was around 9. I added some ph increaser and it raised the ph to 7.8 so I added more and it raised to 7.9. next day I checked it and its 7.6 again and my alk is now 13. now I don't know what to do or why it keeps dropping. im thinking im going to have to do a water change to lower my alk. all my coral look great with the low ph which I thought was strange. I always keep my ph around 8.2 and have never had a problem before. only difference is I turned the furnace on in the house and theres a natural gas wall heater right outside my filter room. so im thinking its a co2 problem. any suggestions would be greatly appreciated. thanks.

 

[Sakura2282]

Having high CO2 will cause low PH levels.

 

[Reefer69]

Air out the house, see if that makes a difference, otherwise as long as ALK is good, dont sweat the pH.