- Aquarium CO2 Monitor Carbon Dioxide Glass Drop Checker with 15 ml Monitor Fluid - Color coded indicators for easy CO2 assessment: Blue means CO2 is too low; Green means CO2 is normal; Yellow means CO2 is too high. Excess CO2 can cause fish and shrimp to die from oxygen deficiency. - Concealed glass groove for easy opening and filling with monitoring liquid. - Benefits: provides a simple, visual method to track CO2 levels, helping you avoid under- or over-dosing and maintain a healthy aquarium environment with minimal maintenance. - Key attributes: glass drop checker construction; includes 15 ml of monitor fluid; convenient fill access via concealed groove; designed for aquarium CO2 monitoring. - Use scenarios: - New planted aquariums: insert and monitor CO2 levels during setup to dial in dosing. - Mature planted tanks: regularly check CO2 to maintain stable levels and prevent oxygen-related stress in fish and shrimp. - Shrimp or delicate fish setups: monitor CO2 to avoid high levels that could affect inhabitants.