NOTE: Please trim your pets' nails before use to avoid causing damage to the pool. Please always put up on a hard smooth surface, no sharp items underneath.It keeps the bottom stretched mostly flat, avoid tears caused by sharp items. we suggest the water in the pool is about 60-80% Suggest Water Capacity of size XXL is 96-128 gallons Suggest Water Capacity of size L is 54-72 gallons Suggest Water Capacity of size M is 37.2-49.6 gallons Suggest Water Capacity of size S is 15.6-20.8 gallons