What should be used to clean birdbaths? Currently, I just spray a strong stream of water from the hose.
-- John Wolf, Levittown
You're off to a good start, but are missing some crucial steps. Algae thrives in stagnant water, and fallen leaves, feces and debris compound the problem, so birdbaths should be properly disinfected when cleaned. Here's how, in four easy steps.
1. Drain the basin and rinse it with the strongest stream of hose water the birdbath will tolerate (Concrete ones in good condition typically can handle a jet stream; more delicate basins may not. Use your judgment to avoid damage.) Direct water to loosen affixed solid waste and debris.
2. Fill the basin with nine parts water and one part chlorine bleach to a level above the highest stain. Soak for 15 minutes. (If you want to multitask and leave the area during this time, cover the birdbath with a large wooden board or plastic trash bag (tied into place) to protect visiting birds from the chemical.
3. Uncover and drain the basin, taking care to keep water away from plants, grass and birdseed. If that appears unavoidable, pour the water into a large bucket and dispose of it elsewhere. Rinse until you can no longer detect the scent of bleach. A minute or two is usually sufficient.
4. Allow to air dry under sunlight for about two hours to allow any residual bleach to dissipate before refilling with clean water.
-- When refilling birdbaths between cleanings, drain and refill instead of topping off stagnant water.
-- Keep baths filled nearly to their tops.
-- Stagnant water can become a breeding ground for mosquitoes. Drain and clean two or three times per week -- for the birds' sake as well as your own.
-- Consider adding a natural enzyme and beneficial bacteria product to help keep water clean and clear.
-- Bleach is no more harmful to birds than it is to humans if it is thoroughly rinsed away and exposed to fresh air and sunlight, as advised above. Still, if you are opposed to using it, you can substitute white vinegar. You may find you need to scrub a with a nylon brush to remove algae completely. Regardless, be sure to rinse well after soaking.
-- Adding a few copper pennies (or small piece of copper pipe) to the bath will retard the growth of algae.