Hello fishfolks, I wondering if any of you out there know the toxicity of either potassium sulfate or magnesium sulfate. Specifically, up to what levels can these substances (Mg, K and SO4 ions) be considered safe in an aquarium. This question does not seem to have been addressed in the archives. Thanks in advance -------------------------------------------------------------------------- James Wong u2120863 at acsusun_acsu.unsw.edu.au