Hi all, I've got myself a new fish tank but its all gone cloudy, and I'm not sure what to do now! I bought the tank (18x10x12"), which came with an undergravel filter (a plastic sheet type thing) and an air pump which I've got on the back right hand side. Its only been on low setting, but Ive put it onto high now. I cleaned the gravel, but after speaking with some people, it might not have been done enough. Anyway, I had it running for a couple of weeks, but it got a tiny bit cloudy. However, as soon as I put in 1 fish (a fancy goldfish type), its gone really foggy within a week!! I've tried cloud cleaner product, gravel cyphoning, and 2 other bottles Stress Zyme and Stress Coat. I've also got some plants in there now too. None of these has really made an impact! The pet store just keeps selling me more bottles of stuff to try - which just aren't working and each one is at least a fiver a time. I suspect that I haven't cleaned the gravel enough before I put it in? However, the pet shop guy says that I must not empty the tank and put in new water, as this is bad for the fish! Can anyone offer some advice as to how I can clear my tank - I'm stuck and can't find any references in books/web as to how to actually combat this - other than what I have tried. If I empty the tank and clean the gravel, then put new water in will it kill my fish? Anything else I can do? What about 1/3 of the water every week, or will I still have lots of fog, as I'm not actually cleaning the gravel. I'm a bit worried about my new fish! Thanks people!