Ultimate Turtle & Tortoise Health Conditioner Block has been formulated to slowly release calcium and vitamin D3 to prevent softness of pet turtle or tortoise shells and provide a source of essential calcium for your pet turtle or tortoise. Vitamin D3 assists in the absorption of calcium from the intestinal tract. Also conditions the water by neutralizing acid water stabilizing pH. 1 block will treat up to 15L of water. Recomended to be used in conjunction with a UVA and/or UVB globes.