The chemical smell of chlorine is familiar to anyone who has been swimming in a pool. Not only does chlorine cause red, itchy eyes and brittle hair, it’s been linked to health problems and allergies. A non-toxic alternative is hydrogen peroxide, which keeps your pool sparkling clean without unpleasant odors.
How Hydrogen Peroxide Works
When exposed to ultraviolet light, such as sunlight, hydrogen peroxide reacts to create compounds that oxidize and eliminate organic nutrients that would feed bacteria and fungi. This reaction takes place quickly, meaning that frequent use of the pool will require regular testing of the water with test strips to ensure an adequate concentration. Plan to test your water at least weekly to maintain the desired ratio.
Shocking Your Pool to Control Microbes
To begin using hydrogen peroxide in your previously chlorinated pool, it’s not necessary to drain the water. “Shock” the water by adding 35 percent concentrated food-grade hydrogen peroxide at a ratio of one cup to 250 gallons of water in your pool. Start the pump to circulate the solution and then shut off the pump to allow the peroxide to work for 24 hours before swimming. You may skip this step if your pool has been recently filled with fresh water.
Ongoing Care of your Pool
After the initial shock, test your pool weekly to ensure an adequate concentration of hydrogen peroxide: typically 30-50 parts per million for residential pools, up to 100 ppm for higher-volume pools. This concentration is approximately one cup of hydrogen peroxide for 500 gallons of pool volume. Peroxide testing strips are available at pool supply stores and are easy to use: Dip the test strip in the pool and compare the color with the packaging.
Pool Hardware Concerns
Hydrogen peroxide should not be used with diatomaceous earth pool filters, as high concentrations can turn the filter to sludge. Natural rubber fittings or accessories are vulnerable to oxidation from hydrogen peroxide and should be replaced with artificial substitutes. Indoor pools must employ an ultraviolet light system to activate the chemical reaction that eliminates microbes; hydrogen peroxide is not an effective disinfectant by itself.
Storage and Safety
Hydrogen and oxygen molecules recombine to form water and lower the potency of food-grade hydrogen peroxide, so it’s best not to buy more than a 30-day supply. Hydrogen peroxide sold at pool supply stores has a longer shelf life. Store hydrogen peroxide in a cool, dark and well-ventilated location. As with any oxidizer, handle hydrogen peroxide with proper physical protection, including neoprene gloves and safety goggles. Avoid skin contact and inhalation of concentrated hydrogen peroxide.
