When I first took over the pool I assumed the main drain line was plugged because I could swim right up to it with pump running, place my hand directly over the cover, and feel not one whit of suction. Then as time went by I realized it must have some degree of suction because I noticed leaves congregating over the cover when pump was running. But still I considered it a minimal source of suction in the system.
So today as I was performing routine maintenance, I notice the pump strainer basket is *crammed* with big pecan leaf stems that could only have come from the main drain. They don't float because they are heavy, and besides, there were none in the skimmer basket. So long story short, main drain is obviously operating normally. But I tell you, you can feel not the slightest whim of suction if you hold your hand over it! How it is able to not only draw in, but suck the big stems all the way up to strainer basket is beyond me!
Anyhoo, carry on...just an observation...
So today as I was performing routine maintenance, I notice the pump strainer basket is *crammed* with big pecan leaf stems that could only have come from the main drain. They don't float because they are heavy, and besides, there were none in the skimmer basket. So long story short, main drain is obviously operating normally. But I tell you, you can feel not the slightest whim of suction if you hold your hand over it! How it is able to not only draw in, but suck the big stems all the way up to strainer basket is beyond me!
Anyhoo, carry on...just an observation...