PH Levels OK?

I have heard many times that it is better to have a stable PH than to keep using stuff to change it and have it bouncing around. Mine is stable at 7.9 which is listed as OK on the test, but is lower than I would like since most fish are sposed to like it a bit higher. Would this be OK for a yellow tang? I have two clowns and a couple pajama cardinals right now that seem to have no problem with it. Just added a royal gramma...too soon to tell. What is your opinion. I have a buffer the fish store sold me, but haven't used it since I been researching.
KathyW

Thanks great article! So since I am in the just "ok" but not optimal zone...shall I try that tang?
KathyW

It is a 55, but the tang is only going to be in there to grow out a bit, I am planning a much larger tank, (as large as I can pull off with my hubby), in my sons room when he graduates and leaves this Summer or Fall. I am learning on this one, and already planning my next one...lol. It will be my 5th and hubby is just now realizing the $$$ I've spent, so it might end up being how big a used one I can find, and he has already agreed to help me with a DIY sump. I saw a 225 gallon on ebay within driving distance with all the goodies for a steal, but at the time I had not even filled the 55 up with water yet, lol, and my darlin, well, he just gave me that googly eyed look that Ricky Ricardo used to give Lucy, so I let it go...(for now) heehee. But my new hobbies room NEEDS a tank, don'tchathink?
KathyW