It's normal for your tank to initially become cloudy. The beneficial bacteria that digest the fish waste colonize only on the surface areas in your tank. They form in a layer, one deep, on any surface that has oxygenated water passing over it. The cloudiness in the water is an initial bacteria bloom that you'll see as the colonies start to establish. Don't panic and try to get rid of it with chemicals or a UV sterilizer, you'll just slow the process down. Patience is a virtue, but I usually have to remind myself of that as I'm shopping through Ebay looking for any to spare!