also another question regarding pH...mine is high ranging from 8 to 8.4 but is and always has been extremely stable. I have some new angelfish (1 koi [2 have died since introduction yesterday, even tho i was slow to acclimate about an hour which I'm thinking wasn't long enough. I hear the kois' are more sensitive...] and 3 black marble which are doing very well [eating, swimming, being social, ect]. Short of my high ph, my other parameters are good (nitrate, nitrite & chlorine are all undetectable). Other inhabitants are 3 glass catfish, 2 gouramis, 3 otocinclis, 2 true SAE and a male & female betta, all of which have been long-time inhabitants and are doing very well. BTW, this is a 60 gallon planted tank with driftwood but without CO2 injection, which I am not intending on purchasing. I live in the country with water from my well which is naturally hard and alkaline. I do have an RO unit for my 120 gallon reef tank so I have the ablility to change the pH/alkalinity but am a bit apprehensive given the fact that I don't want to initiate crazy swings in the pH. Do you think I should leave well enough alone or attempt to do some partial changes w/the RO water? If I do that, will the alkalinity stabilize enough to keep the pH in a more neutral range? Thanks in advance for words of wisdom...