Deep Clean 5 is a liquid internal pipe cleaner for hot tubs. Its acidic formula with a pH of 2.0 is designed to loosen biofilm deep in the hot tub’s water lines. Deep Clean creates an unfavorable environment for biofilm to live or proliferate, lowering the pH to an adverse level for these organisms. Its acidic formula also loosens scum, oils or sludge, bringing it into solution so that it can be drained away. The ‘5’ in the name refers to the five steps in add, run, drain, clean, fill – this is a single use bottle for one draining sequence.