What is a Main Drain
A Main Drain is a suction point located at the deepest end of a Swimming Pool. Although a Main Drain can be used to empty the Pool of water, this is not its primary job and is rarely done. Instead, a Main Drain is used to circulate and filter the water alongside Skimmers. Whereas Skimmers ‘skim’ the water’s surface, Main Drains suck in water from the lowest point and sends it through to the Filtration System.
How a Main Drain works
The Main Drain uses suction to pull in water from the bottom of the Pool. Any dirt or debris that has not already been caught by the Skimmers and allowed to sink to the bottom, exits the Pool though the Main Drain and is caught in the Pump Basket before the water continues through the Filtration System.
A Main Drain should be covered with grates or antivortex covers (a cover that diverts the flow of water to stop a dangerous vortex from forming) to prevent people from getting their hair caught or even worse themselves!