There's always the Bromine option with hot tubs too (not sure for pools), but I never cared for the "smell and feel" of bromine. Chlorine gives me the "hey this smells and looks sanitary" kind of results, which is good considering you have a stag party, there's 10 guys in the tub (I have a 550 Imperial gallon tub at the lake), which is pretty much a ballsack, penis, and hairy man arse soup. You bet I want chemicals in there, screw the hippy stuff!
