Blue dream

If you have the ability to do it it's amazing! It's not the cheapest entry and depending where you are refills can be a pain but if those are no issues adding co2 is great for the plants. More co2 means the plants can take in more light, increasing growth and yields. Co2 is the energy plants use to convert the light to food. It would require s good light source though because co2 on it's own is not plant food and wont make the plant excell on it's own. Co2 is the key that unlocks your lights true potential.