Tank trouble!!

[Aquattro]

So after going home for lunch (had some great chili), the clam is looking better than this morning.
Testing pH shows the tank at 7.9 and the effluent from my reactor at 7.6. Looking at things with the lights on seems to indicate the corraline going white where the return water flows. Although the other big white patch also has a power head beside it.
Any tips on raising pH permanantly without a refugium? My skimmer is big and aerating the water very well.
Could a pH of say 7.7 or 7.8 affect areas of contact like this? I'm guessing that the pH was below 7.9 first thing in the morning.
Any ideas given this info?

BTW, thanks to Shane for his help. Didn't even know the guy and he lent me equipment!!