Confused about plumbing skimmer/main drain

[Shane1]

We had a bunch of family stay over the weekend and I was trying to explain to my bro inlaw how the pool plumbing works. He asked what happens when/if the skimmer gets completely clogged. I told him that it just automaticaly starts pulling water from the two main drains. So I plug one of the holes in the skimmer with a tennis ball and the pump runs dry . I thought for sure it would pull from the main drain and I could have sworn i've done it this way before . We tried several times with the same results. So fast forward to today, I put my diverter in the skimmer, hold the wier door closed and shazam the diverter float drops and the pump starts pulling from the main drains . So whats the difference between the diverter shutting off the water supply or another device or debris?
Thanks

 

[jblizzle]

Do you have 2 holes in your skimmer? One goes to the pump and one goes to the floor drains.

If you plugged the pipe to the pump ... it will run dry.
The diverter just drops the float when the water level drops which then forces the water to be pulled up the 2nd pipe from the floor and then in the pipe you put the ball in.

If the pipe between the skimmer and pump gets clogged with debris ... it will run the pipe dry ... just like the ball did.

 

[Shane1]

Yes, two holes in the skimmer. So the only path for water from the main drain is through the skimmer?

 

[jblizzle]

That is one way for them to be plumbed (both my pools have been that way). And based on what you described ... that is what I would assume.

Do you have the spaceship diverter? The little float gets sucked down if there is not enough water in the skimmer thus making the pump pull from the main drain. There should be a slider that if you close it, will result in more water pulled from the floor.

 

[Shane1]

LOL yeah thats a good description of the diverter. The slider broke off a while back though. What you are saying makes total sense. Thanks