I think that distilled water starts out at a ph of around 6-6.5, but usually DI water is closer to 7. Over time, both will drop in pH unless you buy specialized housing for the DI water. Since many people doing IHC at my university are using RO water, which has a pH similar to what the pH of the tap source, I would say you are probably okay going with the distilled water. My word of caution is to check the level of air in your housing tank and never let it drop below half. Typically, the more air in the tank, the more CO2 going into the water which will gradually lower the pH down to 5.1-5.5 territory. Also, if you have the option to chose between using a glass carboy and a plastic one to store water, always go with the glass. While all of this has never been a real problem for me in terms of analyzable results, I often wonder if it has anything to do with why, sometimes, identical staining procedures on identially fixed tissues will stain notably different.
Matt Close Department of Biological Sciences Lehigh University _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet