To clean a fresh-water fish tank once per week, 10 to 15 percent of the existing water should be removed, and the gravel and decorations should be cleaned using a siphon. Additionally, an algae scraper should be used to remove algae. Refill the tank with clean, chlorine-free water as close to the original water temperature as possible. It is not necessary to remove the fish from the tank.
For a more thorough tank cleaning, the decorations can be removed and scrubbed with an algae scraper. Harder-to-clean items can be soaked in a solution of 10 percent bleach for 15 minutes. It is important to not use soaps or detergent, because left-over residue can be harmful to fish.
Vinegar and water can be used to clean the outside of the tank. Standard glass cleaners contain substances that, if they find their way into the water, can be harmful to fish.
The filter should not be cleaned at the same time as the tank, because it is important not to eliminate all of the good bacteria at once. It is also advisable to replace one part of the filter at a time. However, if the filter is damaged, it can be entirely replaced.