In order to clean your fish tank, you will need the following: a bucket, water conditioner, aquarium salt, a clean filter, a suction tube, and clean fresh water. Remove the lid and the light from the aquarium. Unplug filters and heaters. Remove all plants and decorations from the aquarium. Place them on a towel on a protected surface. Place the large end of the suction tube in the tank. Suck on the smaller end. When water starts to come up, place it in the bucket. Drag the tube along the bottom. Make sure that the bucket that doesn't over flow. Empty the bucket, when it is full. Use a clean filter to clean the walls of the tank with a filter. Never change more than 50% of the water. Condition and salt the water, based on the fish that you have in your aquarium and the instructions on the bottles. Pour the water into the tank. Change the filter.