Clean as in like when theres already fish and such, or like to be able to put it in the tank.
Oh gosh -.- I sure had an experience. I sat in my bathtub for HOURS trying to clean my sand. I got regular play ground sand and was going to use it in my five gallon. First: I used a t shirt, thinking that would be easy to do, just set the sand on top and let the water run through, thus cleaning the Sand. Nope, didn't work
Then I put it in a bucket and swished it around for ever, letting the water overflow out and then dumping it sometimes. That's a lot of water.
Eventually, I ended up using the Betta cups and just getting a TINY bit and cleaning it that way.
It took too long even for the five gal so I eventually just dumped the sand in and continuously swished it around and had the water overflowing.
It looked like it worked but eventually it was dusty looking again, and my betta didn't like that so I eventually went back to gravel :/