Best way to raise ph? Kalk?

[LeanneP]

I have a 4 years old mixed reef 90 gallon with 10 gallon sump. My tank is pretty full and I have started to have ph swings now. I am in the process of setting up a calcium reactor but have been dosing for a couple of years now. My ph is going down to 7.7 at night now so I know I need to do something about it. Is kalk the best way for the ph swings? Would using a doser at night and dosing once an hour be enough to stop the swings? Or would it need to be dripping constantly to keep it stable? I do have an extra aqua lifter so wondering if that would work.