hello evryone. by the way, sorry about the multi posting. i was wondering. i bought a Penguin 125 bio-wheel for my 20 gallon tank. will it keep my aquarium crystal clear like i would want it to be? and my 2nd question is how long will it take if i put sand in my tank,for the cloudiness to go away?? and should i put the sand, or the water in the tank 1st ?? thank you!