The OnePen from Bluelab is the ultimate 3-in-1 precision tool for growers who demand fast, reliable nutrient insights, as this handheld device measures pH, electrical conductivity (EC), and temperature, helping you optimise nutrient uptake and plant health with confidence. Featuring a replaceable double-junction pH probe, titanium EC electrodes, and an IP68 waterproof design, it’s built for durability in busy grow spaces, just like the brand’s Soil pH Pen and pH Pen. The bright backlit display shows simultaneous pH and EC readings with 0.01 pH precision, while Bluetooth connectivity lets you sync data to the app for real-time tracking, history storage, and seamless measurement management. Whether monitoring nutrient solutions, runoff, or water sources, this intuitive tool boosts your workflow and supports informed decisions that boost overall harvest quality.