Thank you all for your advice. I tested my tap water and it is the same as the tank although I know that three weeks ago my tap water was about 40 ppm higher in Gh than it is now. I think that I shall go buy some Seachem acid buffer. How often should I check the Ph after I reach my target ph? Is once a week often enough? I want to set up a new tank using profile as the substrate. Will this raise Ph? It is a fired clay product. Teresa ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!