One picture shows a crack on the top of the skimmer where it touches the concrete. Because it is above the water, could this be sucking in air?

There is also a crack under the water, but it can't be sucking air, can it?

What do I use to seal the cracks? Same product for both cracks?
Thanks for any help.

There is also a crack under the water, but it can't be sucking air, can it?

What do I use to seal the cracks? Same product for both cracks?
Thanks for any help.