My brother used that for his tank.
All you have to do is give a very good rinse.
Put some sand in a NEW/never used bucket,put the bucket in your tub,fill the bucket with water, then use your hand to stir the sand a bit, pour the water out. Do that a few time till the water runs clean enough so you can see the sand in the buck.
Oh and clean out your tub BEFORE YOU USE IT AGAIN. Don't ask why. I think you can think of it.
DONE.
I would wait to put you fish for a bit. The water will not be to cloudy since you rinsed the sand before hand.
Also do half or 1/4 of your gravel at a time if you changing over to sand, then wait 2 weeks before removing more gravel.