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Dealing with vinyl liner stains

Pool tar

Sticky substances often referred to as ‘pool tar’ or ‘pool goo’ can adhere to, and cover, parts of a vinyl pool liner and appear as a stain. These substances are sometimes caused by the interaction between quaternary ammonium compounds used in some algaecides and decaying organic material such as leaves, grass and insects.

Sticky substances often referred to as ‘pool tar’ or ‘pool goo,’ which are sometimes caused by decaying organic material such as leaves, grass and insects.

Chlorine can also interact with quats to form a sticky material if both exceed the recommended levels. For instance, quats can easily come into contact with high chlorine levels in automatic chlorinators, which can result in a gummy substance being gradually fed into the pool where it will eventually precipitate onto the liner. These substances can form when organic materials from cosmetics or tanning/sunscreen lotions are oxidized by high chlorine concentrations, resulting in a beige waxy substance.

Although it is not harmful to swimmers, sometimes a light coating of vinyl plasticizer material, which turns dark when contaminated with dirt, may rise to the liner surface of newly installed liners during the first idle period of winterization. This is attributed to lack of circulation, as this reaction has never been observed in a swimming pool that has been circulated over the winter. The plasticizer material will typically be reabsorbed or oxidized at the liner surface in two to three weeks if the pool water is allowed to warm up (above 21 C [70 F]) and circulate before being shocked with chlorine (6 to 8 ppm) every other day.

Author note:

The information in this article is based on the strength of high quality, 100 per cent virgin-vinyl sheeting. Low-quality vinyl sheeting and/or inferior inks and printing processes will not likely withstand the chemical hardships described above. Builders should be aware of the quality of vinyl being used in the pool liners they purchase, install and service.


Flieler_Head_ShotCarl Flieler is a product development specialist with Canadian General-Tower Ltd., a vinyl-liner manufacturer in Cambridge, Ont. He is a professional engineer with more than 10 years experience in printed, vinyl-film formulation and manufacturing. He can be reached via e-mail at

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