From: IDMiamiBob at aol_com > It is intended to use with tap water, and works safely > only because the chlorine evaporates out overnight, and > the 25% level dilutes it enough to be harmless until then. Does chlorine only dissipate though evaporation? I always presumed a lot of it combines with stuff in the tank water. -- Cliff Lundberg ~ San Francisco ~ cliff at noevalley_com