<human>:  What is the best way to clean a fish tank?
<bot>: The best way to clean a fish tank is to do a full water change. Start by taking out about 20-30% of the water and replace it with fresh, treated water. Then, use a siphon pump or a floating algae scrubber to remove algae and debris from the sides of the tank. Make sure to rinse any decorations and gravel in a separate container with old tank water. After the tank is clean, add a dechlorinator to help reduce chlorine levels in the water. Finally, test the water's pH and temperature to ensure they are ideal for your fish.