What can I put in the water of my bird bath/fountain to help them and it to keep clean?

gold finches in the new bird bathfountain

Brand new bird bath fountain, gold finches love it. … bird bath fountain gold finches

Elaborate Bird Bath-Fountain!

My parakeets really love this fountian, not only do they bath in they also drink from it. Yesterday, when Star took her bath, she splash one of the blue birds, who absolutely hates the water.