Re: the deionizer. Once the water goes through this the GH =0 and KH = 0. (tested by me) I add Seachem acid buffer and Seachem alkaline buffer, Kent R/O Right. And that's it. The problem is not the water I use during a water change. It remains stable over time when left in the tub. I have 15 gallons of it right now. It was made 2 days ago and it is still pH 6.4 and KH 3 GH 3. The problem is that there is buffer left in the the tank water from the old buffering system. By the way, I checked the water in the tank this morning and it is holding. My fault in this is that when I did a water change a week ago, I did not follow up with more than one pH test. I assumed, very incorrectly, that the pH would remain stable, which it did not. My only other option, would have been to almost drain the tank. In retrospect, I should have checked every hour or so for the first 8 or so hours to make sure the water stayed at 6.6 to 6.8. I like having my fish breed and they absolutely won't even consider it as an option if they are kept in tap. Ironically, it doesn't even seem to be the pH in the final analysis that seems to determine this, but the hardness. My dwarf gouramis and pearl gouramis were building bubble nests and spawning every 4 days last week in spite of the fact that the pH went sky high. Please don't assume that I don't really care about my fish because I do. I am not "experimenting" regardless of their comfort. That is the reason I would like to find out whether it is the phosphate buffer which is screwing around the pH, or whether the Seachem product (contrary to the label directions) is not reliable in providing a stable result. This would be a big disapointment, because my intention has been to simplify, and not complicate things. ------------------------------------------------------------------------- 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"!