But when those waters become green and filled with slime and algae, the effect is not only no longer beautiful to look at, it can become a source of foul odors, mosquito and other insect breeding and a potential health hazard.
To keep outdoor fountains sparkling and clean, treat them to a regular draining, cleaning and refilling with fresh water. To kill slimey algae and overabundant growth in the fountain an application of sodium percarbonate in the cleaning process is recommended.
Sodium percarbonate is a dry form of hydrogen peroxide used in cleaning and agriculture. It is generally available in a 27 percent dilution strength powder. This is a high strength solution and should be handled and applied with care. Use rubber or latex gloves when applying the sodium percarbonate to the drained fountain surfaces for cleaning.
Between cleanings, keep the fountain water fresh and clean by adding 1 to 2 cups of 3 percent hydrogen peroxide for every ten gallons of fountain water. This will keep the bacteria and algae growth to a minimum without harming the fountain or any creatures in the environment who might drink the water it contains.