Pond Care Products. A crucial element for a healthy and beautiful pond is algae control. Quickly eliminate all algae and green water with GreenClean algaecides! GreenClean Granular is great for eliminating blue/green and string algae in water gardens, water falls, ornamental ponds, fountains, and rocks. We suggest these solutions are used at the first sign of growth. GreenClean Liquid is better for green water or pea soup (planktonic) algae. The solution moves to the bottom, making it highly effective in deeper waters.