Foam in a hot tub is caused by a combination of water, air, and surfactants, which are compounds that lower surface tension between a liquid and a gas. When these three elements meet, the surfactants form a barrier between the water and the air, resulting in foam. There are several sources for surfactant buildup, including personal care products like lotions, cleansers, makeup, and laundry detergent, as well as chemical imbalances caused by using cheap chemicals or inaccurately mixing them. Foam can also be caused by dirty water, which can be remedied by changing the hot tub water every 3-4 months. Other common causes of foam in a hot tub include:
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Oils and lotions: Every time you use the hot tub, you can potentially add a variety of oils and lotions to the water, including body oils, deodorant, beauty products, and body lotion.
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Poor water balance: Water with low calcium hardness is a common cause of foamy hot tub water. While water balance alone will not cause foamy water, poorly balanced water reduces the surface tension of water in the same way that a buildup of surfactants will.
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Frequent use: If you use your hot tub often or have recently thrown a hot tub party, this may be the cause of your foam-covered water. Thoroughly sanitizing your hot tub after a party may not be enough to clean your water.
To prevent foam in a hot tub, it is important to use the right chemicals and avoid using cheap chemicals from unknown brands. You can also reduce the amount of oils, lotions, and soaps that you introduce into the water by having a quick shower before using the hot tub to remove most of the skincare products on your body. If foam does appear, there are several ways to get rid of it, including using a defoamer, draining and refilling the hot tub, or adjusting the water chemistry.
