As a hot tub gets more use and people are in and out of the water regularly, dissolved solids that do not belong in the water begin to cause hot tub foam. Shampoos, soaps, lotions, and detergents from skin, hair, and bathing suits all end up in the water, and when the level of solids in the water rises past a certain point, foam begins to float along the surface of the water. Chemicals are available to reduce the amount of foam in a tub, but in some cases, the only option for eliminating the foam is to drain the tub, clean it, and replace the water.
Keeping the tub clean on a regular basis with chlorine or bromine is a good start toward suppressing hot tub foam. Shock chemicals can eliminate bacteria and other oils and chemicals in the tub. When these regular cleaning methods do not work, a foam suppressant can be used. This chemical is added directly to the spa water to reduce or eliminate oils and dissolved solids, though again, its effectiveness depends on how dirty the spa water has become. If these chemicals do not work, it may be time to drain the tub and replace the water.
To prevent hot tub foam from occurring after replacing the water, bathers should shower before entering the tub. Long hair should be put into a ponytail to prevent oils naturally occurring in hair from entering the tub. If possible, bathers should avoid using lotions, soaps, deodorants, and other common body applications before going into the tub. All of these oils and chemicals eventually accrue in the hot tub water, leading to foamy build-up. Detergents lingering in bathing suits can also lead to foam, as can spilled drinks, food, or other foreign objects. Bathers should be careful to avoid dropping objects and liquids into the water while bathing.
A final option to get rid of hot tub foam is to turn the jets on, let the foam develop, and scoop the foam out with your hand or some sort of flat tool. This method, like foam-down products, is only a temporary solution, however, and foam is likely to develop again after time. If the foam is a recurrent problem, drain the tub and clean it thoroughly, making sure to scrub the walls and floor of the tub to remove oils that may have accrued there.