Biofilm in hot tubs is usually caused
by an accumulation of bacteria and
microorganisms that exist in the interior or the piping of your hot tub. Biofilm comes mostly from chemicals in or on the body of people bathing, such as skin oils, deodorants, hair products, lotions and perfumes. Older or damaged filters, imbalanced water and ineffective sanitation can also lead to the formation of slime.
"Too much of this slime will reduce the effectiveness of sanitizers, such as chlorine.