Excellofizz pucks are 100% natural! They're an easy solution for raising the CO2 level in your growroom. Supernatural Excellofizz is completely safe, providing reliable, worry-free CO2. Simply add an Excellofizz puck to a small bowl with exactly 100ml of water. In a 12' x 12' foot room, it will bring the CO2 level up to 1600ppm for a good part of a day. If your growroom is smaller, break the puck into smaller chunks and proportion the water used accordingly. Do NOT place puck into reservoir.