Pro Rep Calcium Substrates can be used as a substrate for many reptiles that originate from arid habitats. If eaten it is unlikely to cause gut impaction and actually provides a good source of calcium as it is made from pure natural limestone. Directions: Spread the substrate evenly over the bottom of the enclosure to a depth of at least 1-2â€ (2.5-5cm). Spot-clean daily and completely replace every two or three weeks, or more frequently if it becomes heavily soiled or wet. Small areas of the substrate can be lightly sprayed to provide local humidity control but avoid making the substrate too wet. If you are using an under-tank heatmat as your heat source do not use a thick layer of Calci Grit as this may cause the heatmat to overheat. Please refer to the heatmat manufacturers instructions for more information.