Seachem Silicone Sealant is top of the line 100% RTV silicone sealant designed to seal and repair freshwater and saltwater aquariums. The formula creates a permanently flexible, watertight seal with a high tensile strength that won't crack, dissolve or shrink from the pressure or stress caused by the weight of water in your tank. The solution provides unmatched adhesion and sports a black color in a 3 oz tube.