>> I usually just lurk and read this list for interest, but I just had to reply to this. The reason you never heard of carbon dust creating carbonic acid in tank water is that it is nonsense. Elemental carbon is relatively inert and in water would do nothing. When oxidized, ie. burnt, carbon forms CO2, which forms carbonic acid when dissolved in water. << I was pretty sure this was nonsense.<g> E-mail from: Karen Randall, 17-Jul-1995