Unplug the filter, heater, and lights
Remove fish only if absolutely necessary
Remove decorations, plants, and rocks if needed
Use an algae scraper or sponge to clean the glass
Siphon out 20–30% of the water
Vacuum the gravel or substrate
Rinse decorations in old tank water
Clean the filter media in removed tank water
Replace only part of the filter media if needed
Refill the tank with dechlorinated water
Match the new water temperature to the tank
Restart the filter, heater, and lights
Test water parameters after cleaning
Clean the aquarium on a regular schedule