I’m thinking of replacing the sand when changing out the tanks. The sand I have in the tank was used and very nasty. It took me a week to get the water clean at setup. It does blow around pretty easy. I don’t know what type it is. It’s not super fine but small. I bought some Live Fiji pink but the more I LQQK at it they are starting to LQQK the same. I also bought some dry sea floor special grade reef sand.