Around the base

[bowl4life09]

I'm struggling on what to put around the base of the pool. They leveled the ground and there's this large gap around the majority of the pool. What can I put around it that's not going to cause any damage?

 

[bkp22]

Mulch, pea gravel

 

[Tnt17tnt]

I did pine bark nuggets myself since the installer said anything more then 6" of gravel or heavy material would void the wall and warranty.

 

[Tnt17tnt]

I did pine bark nuggets myself since the installer said anything more then 6" of gravel or heavy material would void the wall and warranty.

This is about 6" deep here where it's 12-18" deep on the highest end. Granted now deck covers that all.
Edit - pretty funny the 6 year old we take care of is doing a back flip off the ladder in that last picture and knows that's not allowed