thats the first time i hear. i also use kalk reactor , and my ph 8.2 night, and 8.5 during my light on. how do u set up your kalk? did u run it your kalk with regular pump??
If your Ph was 7 then most, if not all, your corals would be dead and your fish would be in pretty bad shape also. I would recalibrate your aquacontroller and if it keeps coming up that low use another test kit to make sure that it's correct.