Question: I have a bird bath in my garden that tends to turn quite green with algae. I’ve been cleaning it by hand, but wondered if I could use algicide from my swimming pool to keep it clean.
Answer: It’s best not to use algicides or indeed any pool chemical in a bird bath. Most of them are at least slightly toxic to birds and you don’t want to poison your feathered friends.
There are commercial products that are designed to keep birdbaths clean like “Songbird Essentials Bird Bath Protector”, “Fountain Fresh” or “Micro-Lift”. All do claim to be non-toxic and say they are enzyme-based, but apparently the product content is proprietary, so it’s far from clear exactly what “bio-enzyme” they contain. Still, many people do find it seems to work.
That said, regularly cleaning a bird bath is something you should be doing anyway, not only because of algae, but because birds are messy creatures and readily defecate just about everywhere, including in bird baths. That means the water can become quite contaminated even before algae show up.
Also, debris (fallen leaves, seeds, dust, feathers) slowly builds up as well and helps feed both bacteria and algae.
Also note that the cleanliness of the water of bird baths is doubly important, because the birds not only bathe in the birdbaths, they drink there too, so the risk of transmitting diseases increases when the water is not clean.
Add to that the risk of mosquitoes laying their eggs in the water, especially when it’s “been around for a while”. Mosquitoes are a possible reservoir for West Nile and Zika viruses. Regularly changing the water will eliminate that risk. (Adding a fountain to the bird bath will also help keep mosquitoes away: they don’t like moving water.)
So, if the bird bath seems fairly clean, just swish it out at least weekly with the garden hose; daily in really hot weather. This changes the water and removes most debris and bacteria.
Also, give the bath a more thorough cleaning at least once a month. Wearing rubber gloves, dump out the old water and clean with a scrub brush, using with nine parts fresh water and one part vinegar. (The National Audubon Society recommends not using soap or other cleansers, as they can strip the essential oils off bird feathers.) Scrub the basin, lip, and any spot where the birds land, perch, drink or bathe. Then rinse thoroughly with running water and fill again.
Just that bit of regular upkeep should keep algae away … and your birds happy!