dirty water container
Featured Stories on BackYard Chickens
Using black water containers is best (you could always paint your existing ones black), since the lack of light inhibits the growth of algae. I would suggest cleaning the waterers regularly with bleach and putting a little bleach in the water (maybe a cap full). Don't worry, all mains water already has chlorine in it, so adding just a little extra will reduce the rate of reproduction of algae.