Here's why:
* Toxicity: CO2 is a gas that can dissolve in water. High levels of CO2 in the water can be toxic to fish and other aquatic life.
* pH changes: CO2 dissolved in water forms carbonic acid, which lowers the pH of the water. Fish and plants have specific pH ranges they need to thrive, and drastic changes can be harmful.
* Sudden changes: Introducing CO2 directly into a tank can cause sudden and drastic changes in water chemistry, shocking the fish and leading to stress or death.
CO2 is typically used in planted aquariums to help plants grow, but it needs to be carefully controlled:
* CO2 systems: Dedicated CO2 systems are used to inject small, controlled amounts of CO2 into the water.
* Drop checkers: These devices monitor the CO2 levels in the water and ensure they stay within the safe range for both fish and plants.
* Regular testing: Water parameters, including CO2, should be regularly tested to ensure they remain safe.
If you are considering adding CO2 to your aquarium, do your research, start slowly, and always prioritize the safety of your fish.