I would suggest you adopt a two part dosing regime like B-ionics two part. Within 3 weeks you can bring stability to your alk, calcium and magnesium and indirectly to your pH.
I will give you a link to my blog on how to initiate a two part system.
Please stop dosing buffers. Buffers have borates in them which artificially raise the level of alkalinity in your tank. It is the carbonate part of alkalinity that is important for your corals, not the borate part.
Your pH as Bret said is okay but it should have a high reading of 8.2. If that is the high reading then that is not ideal.
pH is a matter of how much gas exhange is going on in the tank. the more carbon dioxide that builds up in and around the tank the lower the pH goes. Opening a window overnight in the fish room, using a quality skimmer, making sure there is lots of surface turbulance can all raise the pH.
Here is what you should be measuring and prefered levels:
alkalinity 8.5 -11.5 dkH
calcium 400 ppm or better
magnesium 1300 -1400 ppm
salinity 1.026
pH 8.2
Magnesium levels are very important as they help maintain acceptable calcium and alkalinity levels.
Back to two part b-ionics. Two part dosing is great for maintaining acceptable levels of cal alk and mag but you need to bring them up with other chemicals to start with then maintain with 2 part
Here is one ways to do that:
http://www.reefcentral.com/wp/?p=262
I'd still make sure you get that alk and ca where it need to be for long term success though. 
