>If it isn't coming from the tap or the gravel, then you have something else in the tank >that is dissolving. Figure it out. Just made me think, I have one of those red lava rocks with three big holes in it in my tank. I am not sure what lava rock are made of, but could that be buffering my tank? Thanks! Eric Martina ------------------------------------------------------------------------- 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"!