Hi. Ive had my fish tank for almost a year now. Its a 30 x 12 x 15 inch tank, not sure what it holds. For the first few months the tank was perfect, but one day I decided to clean it and it hasnt been right since. The water goes very cloudy after a few days and makes it hard to see very far into the water. Its not dirty, there is no algae at all on the tank, but I cant get rid of the cloudy water. Ive been doing water changes a lot this last fortnight trying to get it clear. Ive tried changing the gravel, but that wasnt the problem. Ive added a power head, that didnt help. Ive got 2 powerfull air outlets in the tank. After doing some test, I found that, ammonia, nitrate nitrite were 0ppm, and the pH of the tank is 7.8. Im thinking of lowering this to 7.4 but I dont think that is the problem. I cant think of anything else I can do, the fish seem perfectly happy as there doesnt seem to be any problem with the water, but I just dont understand why it is so cloudy. I hope someone can help as I really dont know what to try next. Thank You