Dr. Turtle® is a slow-release calcium block that conditions water while providing a calcium supplement to promote healthy shell growth for aquatic turtles. To use, simply place the Dr. Turtle® Block in your turtles water supply. Additional Information: Turtles require UVB lighting and heat for proper shell growth and development. Provide your turtles with Zoo Med's ReptiSun® 5.0 or 10.0 UVB lamps in addition to Zoo Med's Repti Tuff Splashproof Halogen Lamps. For optimum health, feed your turtles Zoo Med's Natural Aquatic Turtle Food.