To most of us, a pool is, more or less, a large hole in the ground. We do not see most of the expensive machinery in a pool system, due to the fact that it is frequently tucked away in a close pump room. But this is the gear that truly makes the pool work.

The heart of the pool system is the water pump. In a classic pump system, an electric motor spins an impeller within the pump housing. The impeller drives the water from the numerous drains through the filter and back out to the water inlets. Just before it flows into the pump, the water passes through a metal sieve basket that latches leaves and other large remnants that might clog up the pump. Following, the water flows into the filter.

The filters in this system are high-rate sand filters. Sand filters entail of a large tank, made of fiberglass, metal or concrete, encompassing a thick bed of special-grade sand, which has a square-like shape. During the filtering process, dirty water from the pool comes in through the filter’s inlet pipe, which leads to the water delivery head inside the tank. While gravity tugs the water down through the sand, the tiny sand bits catch any dirt and debris. At the bottom of the tank, the filtered water flows through the pick-up unit and out the outlet pipe.

Over time, the collected debris and dirt in the sand slows down the water flow. Pressure gauges at the filter inlet and outlet give the pool upholder an idea of the blockage level inside. If gauges show much larger pressure on the inlet pipe than the outlet pipe, the upholder knows there is a lot of built up debris in the sand. This means it is time to backwash the filter.

To backwash, the upholder adjusts a sum of valves to relay the water flow.He or she closes the return pipe leading to the pool and opens the drainage channel, which lead to the sewer system. He or she alters a valve at the filter to fix the pipe from the pump to the outlet pipe and link the drainage pipe to the inlet pipe. With this procedure, water from the pump pushes up through the sand, removing the debris and dirt. At the top of the filter tank, the dirty water flows out through the inlet pipe and into the sewer.