Is it normal for the pool pump to fill up with water while is still filling up?

It is not typical for a pool pump to fill up with water when it is still filling the pool. This suggests a problem with your setup. Here are some possible causes:

1. Broken or loose suction line: Check the suction line that connects the pool to the pump. Make sure it is properly connected and free from cracks, holes, or tears. A leak can suck air into the pump, which can cause it to fill up with water.

2. Clogged impeller: The impeller is a spinning blade inside the pump that helps move water. If the impeller is clogged with debris, it will not create enough suction to pull water through the pump, causing it to fill up with water.

3. Broken or worn-out seals: There are usually seals or gaskets around the openings of the pump that prevent water from leaking. Check these seals to make sure they are not worn out or broken. If they are, the pump may be sucking in air and filling up with water.

4. Incorrect pump size: If your pump is too small for the size of your pool, it may not be able to create enough suction to pull water through the pump, causing it to fill up with water.

If you have checked these items and are still having issues, it's best to contact a professional pool service to diagnose and repair the problem.