King British Aquarium sealant is a silicone dealant ideal for aquaria building, mounting valves and sealing connections. It gives a permanently flexible, watertight seal and excellent adhesion even under extreme pressure. Suggested Uses: This aquarium silicone can be used for constructing aquaria and fish tanks in glass with or without metal frames. It is ideal for repairing existing aquaria where non-silicone materials have broken down or failed and can also be used for applying fixtures inside or outside the tank, mounting valves and sealing. The sealant will form a tough, water tight rubber seal, harmless to fresh and salt water fish. Must be left for at least 48 hours before adding water.