The Bluelab Combo Meter is a portable Meter that takes measurements of pH, conductivity and temperature within a solution. The correct pH, conductivity and temperature levels of a nutrient solution is critical for healthy successful growth. If you are experiencing problems with yellow leaves, or slow stunted growth, the Bluelab Combo Meter will soon tell you if each parameter is within the plants requirements. Adjustments can be quickly made to get your crop back on track.