Why there is air bubble inside pool pump suction basket?

Why there is air bubble inside pool
pump suction basket?

This a very common problem for every pool owners, especially for new open
pool.

A few bubbles is fine but when t comes to noisy churning and a lot of bubbles
area creating, then it can be assign of a major issue.
There are some common reason of air bubbles in pool pump you should
check:

     1. The level of the pool water is too low and doesn’t cover enough to the skimmer. It is recommended to keep the water halfway to three-quarters up the skimmer.

     2. The strainer transparent lid is not tight. Oring has been damaged. The nut for lid will be damage if harmer is applied for tighten. Basket is not seat in the proper position

     3.Piping Valve connection leakage. Check the union (fitting) between the pool pump and the valves. It is a pretty high chance for missteps when take pump apart.
The most common location of air leakage is the suction union. It can be tested by applying water to the suction & pipe join, where you can see the air bubble inside the strainer is getting smaller if there is leakage and enlarger again when water
remove.