Tank swap nuked tank

[tim the toolman]

I was planning on using my existing sand but doing a very thurogh cleaning of it before hand. I am now reconsidering this.
What would you say the benefit is of using new sand rather than giving the old sand a heavy rinse and using it again?
Anyone who can answer tis feel free.

Also to the op, if you would like I will open a new thread with my questions so I am not hijacking yours.