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What Causes Foam in Water?

Occasionally, some swimming pools may develop foam that sits upon the water. This foam is usually a thin surface layer, white or off-white in color, and it tends to collect in a corner of the pool. This is indicative of a high-organic load in the pool water. In nature at the shore line of seas and lakes, a similar, yellowish material often collects for the same reason; it is the accumulation or insoluble organic debris pushed to the margin by the motion of the water. In nature this is called “gelbstoff” (German for “yellow substance”).

In swimming pools the source of the organic debris can be the human bathers (skin, hair, sweat, etc.) and the products they often carry into the pool unintentionally (suntan oils, moisturizers, hair treatments, etc.). Alternatively, animal material (e.g. insects, etc.) or plant matter (leaves, fronds, spores, etc.) can be sources for organic debris in pools. The build-up is most common in water that experiences heavy bather use, has not been changed out for years, or for which the water filtration is insufficient.

If this problem isn’t dealt with it can contribute to frequently hazy water, high chlorine demand, difficulty maintaining proper water balance, scum build-up at the waterline line, short filter cycles or scaling on surfaces including electrolytic chlorinator cells.

Exchanging out old water for fresh water can improve the situation. The best option, short of replacing all of the pool water, is regular treatment with a pool enzyme product. The best products in this category, like Ultra Zyme® Pro by Lo-Chlor®, are effective against the full spectrum of organic debris commonly found in pools. They are powerful enough to make a noticeable difference within a couple of weeks and, ultimately, remove the organic debris and the associated problems from the pool. Removal occurs when enzymes decompose the organic debris into its smallest components which then off-gas from the water.

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