Milwaukee C66 Conductivity Pen – EC Tester for Hydroponics

A Pocket EC Pen You Can Recalibrate and Repair

The Milwaukee C66 Conductivity Pen is a waterproof, high-range EC tester for checking nutrient solutions in hydroponics, coco and soil feeding. It reads 0.00 to 10.00 mS/cm to a 0.01 mS/cm resolution on a digital display, corrects for water temperature automatically, and uses a replaceable electrode, so a worn probe means a new tip rather than a new meter.

Key Benefits

• High range - 0.00-10.00 mS/cm covers seedlings, heavy feeds and run-off checks.
• Accurate to ±2% full scale, reading in mS/cm that converts easily to ppm.
• Automatic temperature compensation from 5-50 °C.
• Recalibrate when you need to - factory calibrated, with one-point manual calibration.
• Replaceable electrode (MA73076) extends the life of the pen.
• IP65 waterproof - shrugs off splashes at the reservoir.

Why Measure EC?

EC tells you how much fertiliser is really dissolved in the tank. Without it, a feed that has crept too strong can scorch roots and lock out nutrients, and one that has weakened as plants drink leaves them hungry, with slow growth and pale foliage. A quick EC check each time you mix, top up or test run-off keeps nutrient uptake steady.

How to Use

• Measure: remove the cap, switch on and dip the electrode into the solution; stir gently and read once the display settles.
• Convert: multiply mS/cm by 500 or 700 for ppm, depending on the scale your feed chart uses.
• Calibrate: check against 1413 µS/cm solution and adjust the trimmer if the reading has drifted.
• Care: rinse the electrode in fresh tap water after every use to prevent nutrient build-up.

Technical Specifications