What do you use to seal gaps around the pool?

[TDTPool]

My phrasing might be wrong, but after re-opening the pool we clearly had some shifts in concrete, and as part of that I have 'gaps' in between the border and the concrete. I am concerned with leaving it this way due to rain, etc, so I'm hoping someone can tell me what to use.

https://imgur.com/a/OKCZqKJ

- Imgur since too large to upload. You can see the gap around the 'frame'. I wasn't sure if I can use just normal silicone caulk, or something special?

 

[AQUA~HOLICS]

Deck-O-Seal, all the old material needs to be removed and backer rod used to obtain the correct depth for the new material.