My experience has been that if you start using chemicals to try to alter and maintain PH you are asking for problems. Most (not all) fish can live in a wide range of PH if they are acclimated correctly. It is easier for the fish to adjust to a high PH then it is to use chemicals and keep a PH constant. You will end up having PH swings with the chemicals that can cause more harm to the fish then what the original high PH would have caused.