Turn the power to the fountain off at the electrical switch or unplug at the receptacle. Bail the water out of fountain with a cup or, if the fountain is small and light weight, tilt the fountain and pour the water out into a sink or drain.
Mix 1 gallon of water and 1 cup of chlorine bleach in a bucket. Adjust amounts of water and bleach proportionately based on the size of the fountain. Pour the water and bleach mixture into the fountain. Restore the power and allow the mixture to run through the fountain for one hour to clean algae from the pump and kill growth on fountain surfaces. Turn the power off. Remove the water and bleach mixture. Wet a rag with plain water and wipe the fountain surfaces to eliminate algae.
Blend equal amounts of white vinegar and water in a bucket. Dip a scrub brush or soft rag into the cleaning mixture. Scrub stone and concrete surfaces with a scrub brush. Scrub metal and resin surfaces with a rag to avoid scratching the fountain. Scrub the pump with a rag. Continue to scrub the surface of the fountain and pump until no lime scale or mineral deposits remain. Rinse the fountain with plain water. Refill the fountain and restore the power.