Main Drain: The main drain is typically located at the deepest point of the pool and is used to lower the water level, however its primary purpose is to circulate water from the bottom of the pool. It is recommended that about 1/3rd of the circulated water come from the main drain.
A swimming pool main drain uses suction to pull pool water through it. Heavy particulate matter that sinks to a pool's bottom is often sucked away through a main drain.
Many pools do not have them. They are not required. They might add slightly improved circulation and can be helpful for removing debris, but there are ways to counter these without the floor drain. Since you get freezing up there, I would be inclined to cap it off.
Main Drain
Usually located in the floor of the pool's deep end, the main drain's name may be a little misleading. While it can be used to drain the pool, it's seldom used that way. Normally, it performs the same function as the skimmers.
Main drains are not required in an inground swimming pool, however, they are strongly recommended and can be extremely useful in some circumstances. The advantages of main drains are to give you the ability to drain the water from your pool without the use of a sump pump. This is useful when replacing your pool liner.
During normal operation, water flows to the filtering system through two or more main drains at the bottom of the pool and multiple skimmer drains around the top of the pool. The main drains are usually located on the lowest point in the pool, so the entire pool surface slants toward them.
According to the Consumer Product Safety Commission, the pressure on some pool drains can be as strong as 300 pounds per square inch. 1 This kind of pressure can suck in hair or body parts, or trap swimmers underwater and cause them to drown, even if someone is trying to pull a victim away from the drain.
For proper water circulation, it is best to position the flap so that it is about 2/3 closed. This will allow for more flow through the main drain than through the skimmer, which will promote a "bottom-to-top" circulation throughout the pool.
Or, as was the case in this wading pool incident, an open drain can suction organs out of the body. In 1993, Valerie Lakey, 5, was playing in a wading pool at a recreation club in North Carolina when she became caught in the uncovered drain's vortex. The pull was so strong that she was disemboweled.
you can tell if your main drain is working by perhaps putting a leaf on it. If it sticks, its working. In any case though, the main drain is not why your pool is having a problem. It has nothing to do with your pool turning green.
Swimming pool builders often install overflow drains near the rim of the pool that prevent flooding most of the time. If you don't have an overflow drain, or if it is clogged, it is possible for periods of unusually heavy rain to overflow your pool.
Drains and Skimmer
Most pools have one, but larger pools may have multiple main drains. Main drains must be protected by an approved cover. Water is also pulled into the pump through one or more skimmers, located on the waterline. Because they are on the surface, they use baskets to catch floating debris like leaves.
When constructing a new swimming pool, if you are going to use a main drain it is required that you use two. This is due to safety regulations to help prevent Main Trap Entrapment. Main drain entrapment occurs when the suction is so great through a single main drain that a person can become stuck on or in the drain.
Most pools have two main drains, but a small pool may have only one. The drains are positioned at the pool's deepest point.
Pools will need to be drained and refilled every 5-7 years on average, or if there is a major necessary repair. Otherwise, avoid draining your pool if at all possible. Basically, if you want to know when to drain a swimming pool, the answer is when you have no other alternative.
Pool drain accidents refer to drain entrapment. Drain entrapment occurs when a drain's powerful suction traps a child's hair, bathing suit or body parts. Drain entrapment can cause serious and fatal injuries, including broken bones, lacerations, internal organ damage, drowning and brain damage.
Because pool drains use suction to filter things out of the water, they put people at risk for entrapment. If a small, light person gets too close to a pool drain, they can become trapped underwater, which can lead to a host of injuries including accidental drowning.
Skimmer Vs. Drain. If the pool receives a lot of leaves and other debris, more suction may be required at the skimmer than the main drain to adequately strain debris floating on the surface. Conversely, if dirt on the bottom of the pool is the principal contaminant, more suction is required at the main drain.
Although it's generally recommended that all the pool water undergo filtration every 24 hours, the pump does not need to run all the time. A proactive, productive and energy-saving maintenance activity is to remove the debris floating on the pool surface with a hand-held skimmer.
Pool overflow will typically go into your home's drainage system or directly out into the city's systems.
To be safe a pool drain must not be “blockable.” This means one person should not be able to completely block the drain. One way to fix this issue is by installing at least two drains 36″ or more apart.
Pool Overflowing From Rain
Rain, by itself, normally wouldn't harm your pool. However, as rain falls, it deposits pollen and other particles in the air onto the ground and into your pool. Any runoff into your pool will also contain contaminants, which can quickly turn your relaxing, beautiful oasis into a mess.