Sunscreen and Swimming Pools

In Blog by Timothy Petsch

Now that we are in the thick of summer, it is probably a good time to take a hard look at the effect that all those sunscreen slathered bodies are having on the operation of your outdoor pool.

Over the course of any summer we get calls from our clients telling us that they have been forced to close their pool -losing valuable revenue- due to significant cloudiness. Sometimes the health inspector forces the close; other times the operators have the good sense to make the call themselves.

So what is happening and how can you be prepared for this situation?

The ingredients list in most sunscreens is, overall, the same. Homosalate, an organic compound, is a common ingredient and is one that can cause a Pool Operator the summer blues. It is an ester formed from salicylic acid and 3,3,5-trimethylcyclohexanol, a derivative of cyclohexanol. Homosalate has two properties that merit its inclusion in sunscreens: it protects the skin from sun damage and is somewhat water resistant. The salicylic acid portion of the molecule absorbs ultraviolet rays with a wavelength from 295 nm to 315 nm. The hydrophobic cyclohexanol portion provides greasiness to keep it from dissolving in water. This later property is the bad actor here and many sunscreens have it either straight up or, more commonly, bound into the structure of another ingredient. This stuff is not water soluble – that’s its purpose. So when it washes off of the bathers, it builds up in the water and everywhere else.

Enzymes will break homosalate down, so a regular maintenance program will help, as will thorough filter media cleaning with an alkaline cleaner. The enzyme program and filter cleaning will keep the operator ahead of potentially cloudy water and pool closure. I should also mention that the pool walls should be scrubbed regularly, because this stuff is sticky and clings to everything. If there isn’t a positive reading on phosphates in the water I would recommend putting the money currently budgeted for phosphate remover into a heavier enzyme maintenance program. Keep a filter aid in the mix, as it will agglomerate what comes through the recirculation system, and clean the filters regularly with the aforementioned filter cleaner.

All in all, summer and the inevitable lotion drenched bodies around your pool require you to be ahead of the cloudy water and chocked filters. It is my hope that this information provides you additional tools to combat pool closure.