Bluelab EC PenThe ultimate handy solution for measuring conductivity (EC or ppm) and temperature! The Bluelab Conductivity Pen simply tells you that your plants have the right amount of nutrient in your solution and lets you know if adjustments are needed. To feed plants well, we need to know what we're feeding them. Start with a quality nutrient. Measuring the conductivity every day is the best way to avoid over diluting or over concentrating your nutrient