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. Turtles require UVB lighting and heat for proper shell growth and development. Provide your turtles with Zoo Meds ReptiSun? 5.0 or 10.0 UVB lamps in addition to Zoo Meds splash proof Turtle Tuff heat lamps. For optimum health feed your turtles Zoo Meds Natural Aquatic Turtle food.