The ISIS has a smaller foot print than the GENESIS and features a self diagnostic controller. This product is easy to install, and will easily handle up to 1500 US Gallons. Pure bromine is not the same chemical that comes from brominating tablets, powders or liquids. Instead, pure bromine is free of chlorine, binders or other compounding agents-and is virtually odorless. Hot tubs and spas maintained by the ISIS are economically and environmentally friendly. The ISIS is efficient, effective, easy to install and conserves thousands of gallons of water per year. ISIS is the BEST thing to make your spa always clean and inviting.