if the power head isnt fully submerged it will make ur water cloudy. this might sound stupid but i suggest changing your fish to tropical and not cold. you will want to some time. its hard to see if goldfish a mating because you cant tell males from females. goldfish breeders just put alot in a tank and hope for the best. if you want to breed switch your fish to guppys or swordtails. i have a friend that breeds them and has alot of friend wit it. they breed fast and you can tell the males form females 50 feet away. heres some guppys
http://www.liveaquaria.com/product/scateg.cfm?pCatId=1100
http://www.liveaquaria.com/product/scateg.cfm?pCatId=1100