Cheers for that ScottB, you say you dose ALK during lights out, I do it when my lights are on so i think i will change that and see if it helps me.Sorry to hear that @Gary Inwood .
Looking back at your numbers again, your Ph is low. I don't do anything to increase mine but APEX tells me my range is 7.95 (at night) to 8.2. I try to keep it smoothed out by dosing ALK during lights out (when Ph falls).
So, I don't have other experience in raising Ph, but google that on reef2reef or reefcentral and you will see a range of corrective measures.