Bluelab pH PenBluelab pH Pen is a compact and durable pH measuring device that is an essential part of any hydroponic grower's toolkit. Monitoring pH in a nutrient solution throughout a growth cycle is tantamount to a successful yield. Growers demand accuracy; the Bluelab pH Pen measures in increments of 0. 1 pH and is fully temperature compensated. The pen is simple to use and made for a grower environment; with it's two point calibration process and buoyant