Main Drain - plugged? No suction, white plate under grill.


Apr 16, 2010
First, thank you to all those who have contributed to these forums; the information herein has helped me maintain a nice, clean, pleasant pool.

Now, my question: I hired someone to close the pool last year (brand new pool owner), and I don't really remember if they jumped into the pool with a screwdriver or not, but what I have this year is:

Skimmer, works fine.

Main drain: no detectable suction from it, and if I look at it closely underwater or from above, it very much appears that there's some sort of plate just under the protective grill/grid.

The line from the main drain has the red cutoff valve in the "FLOW" position, parallel to the line.

Is there a plug I need to go in with a screwdriver and deal with (with the pump physically turned off and unplugged as well, and the 3-way valve set to Skimmer 100% or OFF, one or the other), or is there something else I need to look at?

Is there a better test than being upside down underwater and watching a helicopter or leaf _not_ get firmly attached to the main drain, and my feet able to almost cover it without noticing suction?


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
The suction should be almost undetectable as the cover is designed to prevent entrapment. What happens when you close the skimmer valve?


Apr 16, 2010
Well, I feel foolish; cranking the three way valve around to 100% main drain allows it to develop enough suction to hold a leaf against the grate, and the skimmer is clearly not pulling much water.

Thank you for answering a silly question.

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