Orange dot goby named digger

[jjh302]

So I recently bought an orange dot goby and named him digger for obvious reasons. My issue is he is excavating the sand from underneath my rocks and I'm afraid they may tumble one day while I'm not home and crack my tank. What do I do? Should I take out all of the rock and sand and put egg crate down then put my rock on the egg crate and fill in sand around it?

 

[Dav3]

Did you put sand in or rock in first? Can you try just pushing the rock down into the sand till it reaches the bottom?

 

[jjh302]

Currently there in about a 3 inch sand bed underneath the rock