Foaming in spas is not uncommon. It can be caused by:
Poor water balance:
Low calcium hardness levels can sometimes promote foaming. If you are NOT using Perfect Balance, adjust the calcium hardness to the proper range.
Build-up of insoluble compounds, such as perspiration, cosmetics, etc. can lead to foaming. Spas should be shocked frequently. They should also be drained periodically. To determine how often to drain your spa, use the following formula:
Volume/(3 x Average Daily Bather Load) = Number of days between drains
Use of algaecide:
Quat-based algaecides (e.g. those containing benzalkonium chloride) foam unless they specifically state otherwise. If a foaming algaecide has been added to a spa, it may be necessary to drain.
Soaps and other foreign substances:
Detergents from poorly rinsed bathing suits can cause extensive foaming, as can any fragrances, bath oils or other warm water scents not especially designed for spa use. Read labels carefully when selecting any kind of spa fragrance.
Spas should not be cleaned with household cleaners. If the water line is cleaned with anything that was not designed for spa use, it can cause foaming or build-up. Household cleaning products should also not be used when the spa is drained. It is very difficult to completely rinse the build-up off the spa walls, and when the spa is filled, this film can cause foaming.
If none of the above are the cause of the foaming problem, or the foaming is slight, use SpaGuard Antifoam Concentrate to eliminate existing foam from the spa surface.