ReptoGuard is a slow release medicated sulfa block that helps control common diseases of aquatic turtles, amphibians, and other reptiles. Helps to control a variety of organisms (including salmonella) for the safety of pets and owners. Use one ReptoGuard per 20 gallons of water. Blocks will slowly dissolve releasing active ingredients. On average, each block will last 45-60 days. Shipping weight: 1/10 lb.