Sand bowl / sand piles????

[mrsgrantis]

Hi All!! new here and have a question.
I recently inhereted 3 cory's (not sure of the variety as I can't find any similar looking ones online) wich joined my 6 danios and apple snail in a 30 gallon tank.
After my friend dropped them off I started reading (should have done this first!) and realized they prefer/need sand as their substrate. I have gravel.
I have heard mention of sand bowls/ piles as an option, but nowhere can I find directiosn as to how to achieve this.

Any help is appreciated!!!!

 

[exhumed07]

I've had cories and they seem to be fine in any substrate. they seem like they tend to like to bury their nose in the gravel and suck up stuff in it. sand is uneccesary unless u want it. as for the sand bowls or piles I have no idea how to do them and I would think that a pile would just settle into the gravel.