All you need is one piece of limestone in your tank and it will cause the pH to bounce. I know. There was a white stone buried inside a piece of Mopani wood in my tank. I could never keep the pH down. Two days ago I carved it out of the wood. It was already loose compared to when I first bought the wood. Acid fizzed on it like crazy. I know it seems ridiculous that one stupid stone could do this, but the pH has not bounced since, and it would do exactly what you describe in your letter. Alex ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@majordomo.pobox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@majordomo.pobox.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!