AquaShade Pond Dye is the only EPA registered product for weed and algae prevention. Aquashade reflects sunlight to control plant growth. Use 1 gallon per acre of pond, 4' deep. Pond weeds and algae needs two things to grow: sunlight and nutrients. You can reduce the available sunlight by applying Aquashade Pond Dye which is an aquatic sunblocker. You can reduce the nutrients available in the pond with our PlanktoniX pond bacteria that breaks down sludge, muck and dead organic debris that is providing nutrients to your pond or lake. Please Note: The following states restrict this EPA Registered Chemical: States: AK, CA, CT, ID, HI, ME, MA, NH, NJ, NY, RI, VT, WA.