Most probably it is due to the new sand! How old is your tank? If it's new which I think it might be since your just adding sand or are you switching from bottomless?
I wouldn't recommend using any chemicals. If your tank is newly setup you can expect to see some red slime occasionally until the tank stabilizes. I would recommend you just siphon it out in any case.
If this does not apply then give us some info on your tank,filtration, setup, etc!
If the sand is new, I agree that waiting a bit is a reasonable approach. At some point, you might need to look at nutrient control. The chemicals all have some risk attached to them, and usually are just a temporary bandaid.