Plants get their nutrient from minerals but they can only get all the right minerals they need if certain conditions are right. Think of nutrients like a lock. pH is the key. A key factor that affects food uptake is whether your solution is acid or alkaline. We measure this in ph. The Blue lab pH Pen also measures the temperature of the solution, as root health is vital to the success of a crop. Temperature affects the growth rate and structure of a plant so a solution temperature of 65 - 72˚F is recommended. The Blue lab pH Pen is the latest innovation for handheld meters. It provides a compact quick and handy way to manage the success of your crop to ensure maximum uptake of nutrients. Teamed with our Blue lab ppm Pen, you have a handy, convenient and accurate system for ensuring optimum plant growth and health. Now isn"t that Handy!.