sand over crushed coral - can it be done?

[BCReefer]

I’ve been looking at lot of ref tanks, either through the net or on person and I kinda like the sandy bottom. The only problem is that I am using crushed coral for the base. Am I able to put down sand on top of it?

I was thinking of getting live sand, washing it (I think??) and slowly scooping it in over a period of a few days. Would this cause a major spike in my parameters?

I have no major reason other than the look.

Thanks
Patrick