Drop Checker Solutions
4.2 dKH measures normal and low range CO2 levels.
8.4 dKH measures higher levels of CO2
The 4.2dKH solution will turn green at 30ppm dissolved CO2, and the 8.4dKH solution will turn green at 50ppm dissolved CO2.
Green color indicates between 25-30 ppm (for 4.2 dKH solution) (and 50-60 ppm for 8.4 dKH) levels ideal for plant growth
Blue color indicates lower levels of CO2; CO2 injection can be increased gradually until the indicator solution turns green.
Yellow indicates high levels of CO2 that can be harmful to livestock, if the solution is yellow lower the CO2 injection and check the solution every few hours until the color is green.
By keeping both drop checkers near green at all times, aquarists that typically maintain higher dissolved CO2 levels can ensure greater accuracy in measurement. Further, dual drop checkers will provide a check on each other for additional measurement reliability.