Cleaning a Tropical Fish Tank
Take a large bucket and fish tank gravel vacuum. Place the bucket below the tank. Now insert the hose into the bucket and tape it to the side to make sure it doesn't pop out of the bucket and spill the tank water everywhere.
Insert the vacuum inside the fish tank and pump it till you see the water flowing into the bucket. Remove about 20% of the tank water in this manner and vacuum the gravel and other decorations.
Rinse the filter cartridge with the tank water and not tap water. Make sure you only kill the bad bacteria while rinsing the filter; not the good bacteria. (Ideally, you should replace the filter every month.)
Use an algae scrubber to remove unwanted algae in fish tank sides and on the decorations, and refill it with lukewarm tap water till the brim. Add the dechlorinator to the water.
Turn on the heater, filter, and other electrical accessories and check back in an hour to make sure it's running properly. You don't have to remove the fish out of the tank to clean a tropical fish tank.
Cleaning a Fish Tank Without Fish
Before you start cleaning the fish tank, you should unplug all the electrical appliances, like the aeration, filter, lights, etc., in it. After that, remove the hood and clean it with paper towels and water.
Remove about 20% to 30% of tank water with a hose or cup in another bucket or vessel. Gently transfer the fish with a net in this water, so that they are in their usual habitat. Do not put them in fresh water as they take time to adapt to a different temperature and habitat.
Scrub the inside of the tank with a scraper to remove unwanted algae from the tank walls and the bottom. Remove all the rocks or gravel inside the tank and wash them or vacuum them with a pump and fresh water. Let them dry well in the sun or heat.
Remove the soiled filter, discard the garbage from the bag, and rinse off the filter with tank water. Add fresh water in the tank and add a few drops of dechlorinator.
Add gravel and rocks back into the tank and switch on the electric equipment to set the surrounding of the water as it was earlier.
Transfer the fish back to the tank; don't discard the old water, pour it in with the fish.