Fill a bucket about half way to the top with the sand, then rinse until the water at the top is mostly clear (this works best outside with a hose for obvious reasons). Put the clean sand in the tank
Do as often as needed until you have enough substrate in your tank.
There will still be SOME clouding so you may want to turn off your filter until the sand settles and the cloudiness is gone. Then you can turn your filter back on.
My cherry barbs are awesome and they are in a 20 gallon with the other fish in my signature. If I had it to do over I would probably increase my cherry barb shoal and reduce or eliminate my black neons. But I like my black neons too, so it worked out LOL. Sometimes my neons and cherry barbs will even school together, which is neat.
With the sand substrate you could go for killi's or some other small cichlid.
I also love cories and they love sand.