Hey guys this is my first post! Recently got back into fish keeping and bought an Aquaone tank kit. It is 75L (around 20 gallons) for cold freshwater fish. I set it up and cycled for 2 weeks before buying stock. I currently have three fancy tail goldfish in there, about 1 inch in length each. I now know this is slightly overstocked for this tank but the guy at the pet store said I should buy 4-6 (!!) of the same size so I'm glad I didn't go with his advice. I got my water tested before adding the fish and it was all fine. I've been doing 20% water changes every 2-3 days since adding the fish a week ago to help with ammonia problems. Basically I have two distinct problems: the first is that the filter on this thing sucks. It is an overhead filter that had two charcoal cartridges. Very quickly I realised that these cartridges were too dense and water was overflowing the chamber and going straight into the outlet causing a very strong current and also meaning that the majority of water was not being filtered. I have remedied this by ditching the cartridges in favour of buying my own noodles and charcoal. I ripped the charcoal and the wool from the cartridges and used this to separate the noodles on the bottom, with charcoal on the top, and covered these with the sponges that came with the tank. I plan to replace the charcoal every 2 weeks or so and rinse everything once a week in tank water. This proves to be much more economical as the cartridges cost like $20 each for a replacement (and hardly even work anyways) and a bag of charcoal is like $10 and will last about 5 changes. I just wanted to check that this is an appropriate set-up for my type of tank? My other question is about an apparent bacterial bloom. My tank water is very cloudy and milky at the moment. This started about 2-3 days after adding fish so I assume it is not just dust from the substrate, but rather a bacteria spike due to ammonia levels. Should I continue to do water changes every 2 days or simply wait? Is there a product I should add to the water to deal with ammonia? I have been adding stress-coat conditioner to all new water added, and been using stress-zyme about twice per week during the set-up and introduction stage. One of my gold fish appears to have some very slight ammonia burns which is why I have been changing out the water as much as possible. He also floats at the top a lot and am wondering if this is due to the ammonia, over-crowding, or oxygen? The filter seems to be pumping heaps of bubbles into the water and the outlet is near to the water line creating lots of disruption so I don't think it's water. Any advice would be greatly appreciated!