I swam down to the bottom of my pool this weekend and noticed the main drain does absolutely nothing. There is no suction there at all. I do not have valves to turn on or off my skimmer or main drain, they are tied together. Strangely, during a leak test last year they determined they are tied together, so I'm baffled as to why there's no suction at the main drain. Should I be concerned that I have a 44,000 gallon pool being circulated by just one skimmer on the side of the pool? As long as my robot is working, the pool stays clean.