OnePen

From Bluelab, the OnePen is a three-in-one, waterproof, handheld meter that measures pH, electrical conductivity (EC), and temperature in nutrient solutions. In addition to insights through the Edenic app, the OnePen on its own features a compact, ergonomic design, a replaceable double-junction pH probe, precise readings with a 0.01 pH resolution, and measures conductivity in EC, mS/cm, CF, ppm 500 (TDS), or ppm 700.