(Resending from correct personality...) pH probes are expensive and chemically and mechanically (and electrically) fragile. I guess the best method is to mix a little distilled water with the soil, then filter out just the water and measure that. /Morgan -- Morgan Olsson, Kivik, Sweden _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist