[Bonanza]

You will probably need to hose out the bird bath daily because of bird poop and bird seed. You will never get mosquitos with clean water.
Do NOT use chemicals.
If you get a bird bath that is smooth or slippery, you will have to put stones or something rough in it because otherwise, the birds will lose their footing. That will make it more difficult to clean, however, but you may also attract butterflies if the water level is not deep.