mas985 wrote:Main drains are not suppose to have a lot of suction for safety reasons. They are really only useful for circulation and even at that, only provide minimal benefit.
Now, anyone that has a regular flushing toilet knows better than that. Main drain is piped with the same O.D. pipe as skimmers and even though it has to overcome the riser of around 9 feet it is helped by the pressure of water above it as well as the pump.
Notion, that it may be there for draining the pool is also an absolute nonsense, because the regular pool pump will burn well before it gets half the job done. ( its very design is not a sump pump).
If main drain was really so useless as some here proclaim, than why is the WC designed with drain on the bottom and not on the side like the skimmers in the pool ??
Is it really so hard to understand? All pool sweep, worth the money, starting with the Polaris ( best on the market for the last 50 years) are designed and built on the very principle that main drain is an essential part of a maintenance of pool, which is a removal of a organic as well as non-organic debris.
Also, that eventually ALL debris that enters the pool surface will sooner or later end up on the bottom of the pool!