Fill a bucket half full with dirty tank water. Add clean water from the tap until the bucket is full.
Catch all of your fish with a net one-by-one. Place the fish in the bucket that is full of tank water and clean water.
Unplug the aquarium's filters, heaters and other electrical equipment.
Drain the tank of water as completely as possible.
Remove two cupfuls of dirty gravel and set them aside. Only having clean gravel in the tank upsets the water balance in the aquarium. This is harmful to your fish.
Remove the rest of the gravel from the tank. Place the gravel in buckets, filling them halfway. Place any decorative rocks in a separate bucket.
Place a hose in one of the buckets containing gravel. Turn the hose on. Stir and rinse the gravel or rocks until the water runs clear. Rinse any other buckets of gravel the same way.
Clean the inside of the aquarium using clean water and a scrub brush or sponge. Wipe the inside of the glass dry with paper towels. Rinse and wipe off filters, heaters and other electrical equipment.
Put the gravel back into the bottom of the aquarium. Mix the clean and dirty gravel well.
Fill the tank with clean tap water. Add de-chlorinator when the tank is full.
Put filters, heaters and other electrical equipment back in place. Plug your equipment back in to your power source.
Catch the fish in your bucket with a net one at a time, and return each fish to the aquarium.