Does CO2 get rid of algae?

It’s a common belief that CO₂ automatically fixes algae problems, but this is not true. A healthy planted tank must have three components in balance — lighting, fertilizer, and carbon dioxide. CO₂ is just one of the primary nutrients that plants need to grow. Many beginners use too much light and fertilizer, so adding CO₂ can help balance the aquarium. However, if a tank has high lighting and CO₂ injection but, for example, too little fertilizer, then algae will appear because of the imbalance.

Let’s use a cookie recipe as an analogy. If you add 5x the usual amount of flour (e.g., fertilizer) to your dough, then you must also multiply the rest of the ingredients (e.g., lighting and CO₂) by 5x, which will result in a bigger batch of cookies (e.g., greater plant growth). However, if you add 5x the amount of flour and then try to “balance” the recipe by only adding 5x the amount of chocolate chips (e.g., CO₂), the rest of the ingredients are not in the correct ratio and will result in a bad cookie (e.g., algae growth).

For more information on CO2 systems in high tech planted tanks, read the full article.