Wildfire Ash & Your Pool

*This article is intended for pools outside of fire zones

Well, What's It Made Of?
Ash from fires that burn lower than 840 degrees Fahrenheit is mostly organic carbon. At a higher temperature, the carbon is burned away and inorganic compounds are left. These include things like calcium, magnesium, and sodium.

The fires in Northern California and the current fires in Southern California not only burned forests but also homes and structures. Because the combustion rate is much higher for buildings, the make-up of the ash is much more different. At a very high combustion rate, the ash can contain potassium and calcium oxides which create quicklime. If enough of this ash gets into the pool and then to the filter, it can create a limestone cement coating on the filter media. Ash from homes and structures can also contain toxins such as lead, arsenic, and hexavalent chromium.

Most of the ash that lands in pool water is also hydrophobic and repels water. This explains why the ash floats and is so difficult to remove by skimming. Changing the charge of the ash by using a chitosan clarifier or an enzyme can help in the removal of the ash.

 What Can I Do?
 Good news. You are already doing most of the steps that can be taken. A regimen of shock, floc, enzyme, phosphate removal, and algae prevention makes for a good remedial treatment. 
• Remove all larger debris in the pool and/or spa as soon as possible.
• Brush all surfaces thoroughly.
• Skim smaller material with a pool net.
• Make sure filters are clean and in operational order.
• Shock the pool to 20 parts per million (ppm) of Free Chlorine or use a quality chlorine-free oxidizer.
• Follow immediately with a clarifier to help send small ash material to the filter.
• Consider using an enzyme to help break down some of the non-living, organic material that can’t be filtered out.
• Follow with a good broad-spectrum algaecide.
• Clean filters are as necessary throughout this process. They may need to be backwashed and cleaned frequently during this time.