I am not an expert on RO units, but I am pretty sure that they do not effect pH. I use a RO unit right now and the water that it makes is very soft, around 10 ppm, but the pH is very high, around 8.2. I use chemicals to lower the pH. You can also filter your water through peat, it will stain the water a bit though. Which is why I don't use peat. My tank is right next to my girlfriends tank that she keeps very clear. If I use peat and stain the water it just looks bad next hers. Eric >The main reason for my present inquiry is I'm looking for ideas on how >to best get water I need to age into a tank. The situation.. I picked >up 10 Altum Angels at a great deal. However, the water company raised >the pH so now I need to alter it. I'm looking into an RO/DI unit for >that because the chemicals are just getting annoying. ------------------------------------------------------------------------- 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"!