Test CO2 Levels in Water?

Question

How can the level of carbon dioxide be measured in ppm in water, like in a fish tank?

Answer 1

Carbon dioxide concentration in a fish tank is normally measured using a chart called a "KH-pH table". You simply measure the pH (acidity or alkalinity, measured using various tools including litmus paper) and KH (carbonate hardness, measured using a testing kit), and then match up the values on the chart to find the CO2 concentration in ppm.