A week after I fully cleaned my tank, thick green algae developed and many brown spots and white patches appeared all over the aquarium. I added fresh start and filter start to my aquarium to remove chemicals and add good bacteria. The temperature ranges from 22-25 degrees Celsius and lighting is on from 5pm to 10pm. The nitrite tests show 0.05mg/l and the pH test showed 7pH. Filter runs daily from 8am-10pm. Also, I feed my fish 3 pinches of goldfish flakes at 10pm and leave filter on for 5 minutes before turning off everything. I have two big white goldfish, 1 big orange goldfish, 3 small multicoloured goldfish and 1 cleaning snake shaped fish. My tank has 80 liters. I change 30% of water weekly. My fish have always got diseases such as swim bladder, blood streaks on fins and gasp for air at the surface of the tank. Two of my fish are currently in a 20 litre tank because they have swim bladder. I added 3 tablespoons of tonic salt and 1 ml of swim bladder medicine. Also the white fish have black spots or stripes on them which they never had. I feel very guilty that many other aquarists almost never have any problems and only have to change their water once a month. If anyone spots anything that I had done wrong, please tell me because I really want the best for my fish. All of my water is green and stinks. If anyone helps, I will be very grateful.