Laguna Phos-X is specifically formulated for freshwater ponds to reduce many of the compounds that encourage unsightly water conditions and foul odors. Phos-X absorbs and traps phosphate, nitrite and nitrate, gradually and safely. As a result, your pond water will be crystal clear and provide ideal living conditions for fish and plants. Phos-X is easy to use and greatly reduces hands-on pond maintenance. Simply place one or more packs of Phos-X in the pond filter to maximize its effectiveness. Replace after 3-month or when algae starts to reappear. For best results, start using Laguna Phos-X in early spring.