I have built the same kind of waterer. If you add a 32 ounce bottle of organic apple cider vinegar to the 55 gallons of water, it will not only prevent algae, but is has several benefits to your chickens. ACV is also recommended for other livestock as well, goats, rabbits, dogs, humans, etc.Hello gang, as you can tell I'm a brand new member to BYC. here is my problem. I built a auto waterer last fall from a55 gallon drum... All went well all winter but as the temps rise I have now got algae in the drum...... What is my solution?