To determine the amount of CO2 dissolved in your tank input the pH and KH from test kit results. Choose whether the KH reading is in degrees of German Hardness (dKH) or Parts Per Million (ppm) and read your result below. The amount of CO2 is displayed as ppm which is also equal to mg/L.
You should strive to maintain a range between 20-30ppm of CO2 in a CO2 injected tank.