Do Pool Chemicals Affect Aluminum?

Proper use of chemicals is key to a safe and sanitary swimming pool. Chemicals are used to disinfect pool water, control algae growth and for several other purposes, so a healthy knowledge of how to use these chemicals is essential for any homeowner considering installing a pool. One important fact to learn about these chemicals is how they may negatively affect the aluminum parts of your pool, by corrosion or through any other means.

Chlorine is the chemical treatment you will be using the most in your swimming pool. Chlorine can have a corrosive effect on aluminum components, but homeowners and swimming pool maintainers are sometimes not aware of this corrosion since the corrosion itself takes on a white or gray color that is easily overlooked. But overlooking this corrosion is a mistake, as chlorine corrosion of aluminum can cause significant metal loss and diminished structural integrity of aluminum components.

According to a test conducted by the International Molybdenum Association, chlorinated water at a concentration of 2 parts per million (ppm) or less causes significantly less corrosion on aluminum than on other metals commonly used in swimming pool construction such as cast iron, stainless steel alloys and carbon steel. However, at concentrations above 2 ppm, corrosion rates of aluminum and of other the other metals tested increased as chlorination levels also increased. Stainless steel was the only metal found to resist corrosion regardless of chlorine concentration in water.

There are very few nonchlorine chemicals that you will need to use when maintaining your pool. Inorganic chlorination agents such as calcium hypochlorite, lithium hypochlorite and sodium hypochlorite, as well as organic chlorinating agents such as trichloroisocyanuric acid, potassium dichloroisocyanurate, sodium dichlorocyanurate (as anhydrous or dihydrate forms) are all used to the same effect as chlorine, so their effects on metal can be expected to be roughly similar.

The good news is that swimming pool chemical manufacturers know that their products will be used on aluminum surfaces and thus will provide explicit instructions on how to safely use the chemicals in a manner that limits aluminum corrosion. Always follow product labeling exactly, and regularly monitor your aluminum swimming pool components for any signs of corrosion.