Eric wrote: "I am not an expert on RO units, but I am pretty sure that they do not effect pH." There are better experts than me at explaining this, but although an R/O unit will not necessarily reduce the pH of the feed water it will significantly reduce the ability of that water to HOLD that pH. No "hardness" (removed by the unit) =No buffering ability. Kevin Korotev Milwaukee, WI USA ------------------------------------------------------------------------- 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"!