Still having trouble with cloudy water in goldfish aquarium.?

Hey guys, i have 8 Common/Comet goldfish in a TEN Gallon aquarium. I Know this is Very Bad, but i do have a filter and have been doing Water changes once per week. This 10g with 8 goldfish is just temporary OKAY? I'm going to buy an 80g tank next month, so each week I've been doing 25% water changes, but the water is still cloudy and always will be. how can i get it to be clear, my dad keeps fish too but he stopped, he said to siphon out all the water, and i said nah, it will kill the fish. So yeah PLEASE!!! help me! i don't know what to do. My goldfish are about 3-4 inches, and i don't want answers like "return them" or "give them to someone with a pond" You see the thing is, i only wanted to buy one goldfish only, but the pet store had a tank up front and it said 8 for $1.00. LOL so i just bought it. I didn't really know about the 10g per fish rule D: but now i do and i've been keeping them for 1 year. Thanks for helping. Appreciate helpful answers.