Do you have test kits for Calcium and Alkalinity? If so then instead of a chemical PH UP solution, you can safely dose you tank with limewater to maintain the PH, just keep an eye on the Alkalinity. Your ultimate goal should be 350+ppm calcium (max 400ish) and alkinity of 11dKH or higher (no higher than 12 or so). PH should be around 8.2-8.4 on average for most critters.

Together they will help get you up to where you need to be and hold it there... just add very slowly and test the params frequently, with time you will find the proper dosage to maintain things. Of course there are commercial products available but the cheap way is to use pickling lime for calcium and baking/washing soda for Alk.

Your critters will be a lot happier for it too!