Why does the skimmer top pop out every time your pump shuts off on above-ground pool?

There are a few reasons why the skimmer top pops out when your pump shuts off on an above-ground pool:

Air pressure: The skimmer top is designed to float on the surface of the pool water, and when the pump is running, the water pressure helps to keep it in place. When the pump shuts off, the water pressure drops, and the air pressure inside the skimmer top becomes greater than the water pressure outside, causing it to pop out.

Improper installation: If the skimmer top is not properly installed, it may not be able to withstand the change in pressure when the pump shuts off. Make sure that the skimmer top is correctly seated in the skimmer housing and that the locking mechanism is engaged.

Debris: If there is debris in the skimmer basket or the skimmer throat, it can block the flow of water and cause the skimmer top to pop out. Clean the skimmer basket regularly and remove any debris from the skimmer throat.

Weak or damaged springs: The skimmer top is held in place by springs, and if the springs are weak or damaged, they may not be able to hold the skimmer top in place when the pump shuts off. Replace the springs if they are damaged or weak.

Here are some tips for preventing the skimmer top from popping out:

Turn off the pump slowly: When you turn off the pump, do it slowly to allow the water pressure to equalize. This will help to reduce the pressure differential between the inside and outside of the skimmer top and make it less likely to pop out.

Install a check valve: A check valve can be installed in the skimmer line to prevent water from flowing back into the pool when the pump shuts off. This will help to reduce the pressure differential between the inside and outside of the skimmer top and make it less likely to pop out.

Clean the skimmer basket regularly: Debris in the skimmer basket can block the flow of water and cause the skimmer top to pop out. Clean the skimmer basket regularly to prevent this from happening.

Replace weak or damaged springs: If the springs that hold the skimmer top in place are weak or damaged, replace them to ensure that the skimmer top stays in place when the pump shuts off.

By following these tips, you can help prevent the skimmer top from popping out when your pump shuts off on your above-ground pool.