wash it out in 5 gallon bucket before you put it in tank, also a pillow case works well to wash it out, I put sand in my tank with 75 percent full water, would be easier to add with no water, to maintain mine, people say gravel vac works good to skim sand, but it never picks up the big stuff, so i just take a fine net and scoope up sand and sorta sift it threw the net, net catchs all big stuff, also try not to let sand get to pump, sand will burn it out.