Nano-Tech Phosphree is a polymer resin that is chemically stable and does not leak any metal ions into the water column unlike metal-based absorbents. “Phosphree is specially designed to absorb phosphate at a much slower pace compared to other metal-based absorbents, giving time for corals to acclimate to the reduction of phosphate in the water column.” Rapid reduction of phosphate in the water column could stress out corals, and in the worst-case scenario, may lead to Rapid Tissue Necrosis or RTN.