Sorry, I wasn't very clear about what was going on with the acid. As suggested by someone on the list a while ago I was using the muriatic acid to test my rocks and gravel. Pour a little acid on the rock, if it bubbles the rock has some basic buffering capabilities, if it doesn't bubble the rock is fine. The muriatic acid was used strictly for testing and was not added to the tank. I am using Seachem acid buffer in the tank to lower the pH. I also am injecting CO2 for my plants, which should help lower the pH. but my pH still wants to rise. Thanks, Eric >Hello Eric > >I no water specialist, but if you have hard water, just adding muriatic >acid wont keep the pH down. I will bounce back up. YOu need a R/O unit >to remove minerals, dissolved solids in your water that are keeping it >hard and alkaline. ------------------------------------------------------------------------- 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"!