CO2 drop checker reagent is a 4dKH bromothymol blue solution ready to be used for continuously monitoring CO2 concentration in aquarium water. 30ppm of CO2 concentration is optimal for good aquarium plant growth without stressing out other inhabitants.
Fill up half of the bulb of the CO2 drop checker with the reagent. It is premixed with 4dKH solution and should be used without adding any other contents or water to it. Place the drop checker in contact to the tank water following directions that come with the drop checker. In a few hours the color of the reagent will change based on the CO2 concentration of the water.
Following the color chart provided on the bottle to determine CO2 concentration in the tank. Replace the reagent every 30 days.