Pool sand filters work by allowing water to cycle through a canister that contains sand. The water flows through the sand with ease, but larger particles are unable to pass through. Once the debris and other particles have been filtered out by the sand, a pump moves the clean water back into the pool. As more debris becomes collected by the filter, the efficiency of the filter will start to increase as well.Fenlin provides you with high-quality sand tanks with factory wholesale price and low MOQ.