Topping soil with BLUE SAND?

I have a gnat problem. Little fucker have been eating my roots for about 3 weeks.. Now I gotta do something about it. I was gonna top the soil with sand to prevent the next lIfe cycle from inhabiting the roots but all they had was these bags of crayola colored sand.

Has anyone every seen any sand like this? Will it affect the plant in any way?
I dont think that it will have any adverse effects on the plants, but my fiancé demands reassurance.

Oh and the crayons sand is non toxic

I think it will be fine if it says that it is non toxic. You'll just have very fashionable pots! Hope the sand gets rid of the little creeps!