Seachem CO2 Indicator Solution is a testing reagent used inside a glass drop checker to monitor dissolved gas levels in tanks running pressurized CO2. It changes colour based on the water’s pH shifts caused by carbon dioxide.

• Blue: Too little CO2 (low gas levels/high pH).
• Green: Optimal CO2 (around 30 ppm, safe for fish and great for plants).
• Yellow: Too much CO2 (dangerous levels/low pH).

How to use it:

• Turn your glass pH checker upside down.
• Add 15 to 20 drops of the solution into the bulb.
• Carefully invert it so the liquid stays in the bulb without spilling.
• Submerge it inside the tank, trapping an air pocket in the funnel neck.
• Mount it away from your diffuser for an accurate reading.