Read/download our Pond Care Guide to identify the most common types of algae and submerged weeds, and to see our handy 4-step program to get your pond ready for summer! Crystal Blue uses a proprietary formula to enhance your pond or lake with beautiful royal blue color and clarity all year long. It clears up muddy ponds, and helps settle out dissolved solids. 100% safe for humans, fish, livestock, pets, birds, swimming, potable water and irrigation. Depending upon rainfall or runoff, treat every 30-90 days. One gallon treats 1 surface acre, 4-6 feet deep. Ship wt 10 lb.