How can I keep my ph up?

[RuGlu6]

not my quote but makes sense.
http://www.advancedaquarist.com/issues/nov2002/chem.htm

Unfortunately, calcium and alkalinity are linked in many ways in reef tanks, and these links can lead to serious problems if they are not fully understood. If, for example, you add too much of a calcium supplement, you will drive down alkalinity as you get precipitation of calcium carbonate in the tank. Likewise, adding too much of an alkalinity supplement can result in reduction of calcium. Consequently, trying to correct one problem can cause another. Moreover, if you try to correct a calcium or alkalinity ?problem? with the wrong type of additive, you might accomplish nothing more than creating limestone in your tank.