Hot Tub SERUM Total Cleanse is an easy to use jell designed to deep clean your customers spas of sludge and bio-matter. It is the only product in the spa industry that will completely clean and purge a spa in 25 minutes. Hot Tub SERUM Total Cleanse is so powerful ½ of a jar will clean a 350-400 gallon spa twice or a 700 gallon spa once.