How to change water in an aquarium effectively?

To change water in an aquarium effectively, follow these steps:

1. Use a siphon to remove about 25-30 of the water from the tank.
2. Use a water conditioner to treat the new water before adding it to the tank.
3. Gently pour the treated water back into the tank to avoid disturbing the fish and decorations.
4. Repeat this process regularly to maintain a healthy environment for your fish.