Sand Gravel then water

[citroen]

I am just setting up a 60ltr tank, the rear half is gravel and the front is white sand, there is a tile partition that separates the two.
Is there a good way to add the water ?

 

[grattu]

Put a dinner plate in the tank and slowly pour the water into the plate

 

[citroen]

It sort of worked, the gravel floats, only small parts then sinks on top of the white sand but not the end of the world.
My next job is to sort out some lighting.