The Exo Terra Moss Ball helps provide crystal clear water and reduce odors. Designed to resemble its natural counterpart, the Exo Terra Moss Ball contains a special absorption resin that helps reduce many of the compounds that encourage unsightly organic matter accumulation.By absorbing and trapping phosphate, nitrite and nitrate within its core, the Exo Terra Moss Ball helps to create ideal conditions for animals and plants and makes aqua-terrarium maintenance easy.Key Features :Traps phosphate, nitrite and nitrateEasy and effective deodorizerReduces organic matter accumulationEffective for up to 2 monthsTreats 30-60 liter (10-20 gal) terrariums