Lake and Pond Sustain is an all-season treatment that utilizes natural bacteria to digest suspended dead organics to help keep the pond balanced and the water crystal clear. Lake and Pond Sustain is specifically designed to start working the moment it hits the water. Can be used all season long in water temperatures as low as 38 degrees Fahrenheit works best when water temperatures are above 50 degrees Fahrenheit. Safe for use with fish, plants, birds or domestic animals that drink from the pond.