brs doser

So I'm using a classic Apex system with an EB 8 and a BRS doser 1.1 ml. I slowly add kalk throughout the day and it's at a constant rate every hour. At night the tank will drop in PH even though I'm dosing kalk. So far Ive got my PH up to 8.2 and it will drop down to about 7.98 when the lights...