Are All Main Drains Created Equal?

[elsie]

I think the pic Cleancloths posted is mine:

Sta Rite 8" Anti Vortex 0712-0741

Manufacturer: Sta Rite

Maximum Flow, ANSI/ASME A112 Rating
60 GPM

This cover is A112 approved at 60 GPM

The Sta Rite cover is flat on the top with a circle in the center. Water is drawn in on the elevated sides..

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If the valve were open, I would not be able to feel water being pulled in? SO maybe mine is open after all? I'll dive down this weekend with a vial of dye to see, just for the heck of it.

[Rangeball]

I have an 15+ year old 16'x32' IG vinyl liner pool, 3.5' shallow end and 8' deep end. One skimmer, one main drain centered in the deep end and one return paralleling the 16' side in the shallow end. With only one return it needs the main drain to ensure adequate circulation, and I run both the main drain and skimmer wide open, closing the main drain only when vacuuming to maximize suction.

My main drain has a circle grate cover. The actual 1.5" outlet is in the side of the "bowl". Although you can feel the flow when you cover the grate with your hands, it is well dispersed since the cover is 8" from the 1.5" outlet so suction is minimized. I can't imagine anyone getting stuck to it.

[elsie]

I guess the cover would have to rupture somehow (earthquake, or a shift in the ground), then depending on the GPM, it could hold a person to it?

How in the world do you close that drain to vacuum without diving down and manually closing it?

[Rangeball]

There is a valve before the pump that shuts off the main drain line.

[elsie]

How handy is that. My pool's about the same vintage, too bad it doesn't have one of those.

[Rangeball]

elsie, if you have enough exposed pipe between the ground and the pump, valves can be added, either DIY or paying a plumber to do it.