Conductivity Pen by Bluelab — Fast, Accurate EC, PPM & Temperature Testing
BL-MTR-ECPEN
Pairs well with
The Bluelab Conductivity Pen tells you exactly how strong your nutrient solution is, in seconds. Dip it in your reservoir and it reads EC, ppm 500 (TDS) or ppm 700 plus solution temperature on a backlit display — so you know whether to feed harder or back off before your plants tell you the hard way. It's factory calibrated, fully waterproof, and built by Bluelab in New Zealand for grow rooms, not laboratories.
Specifications
0.0–10.0 EC / 0–5000 ppm (500) / 0–7000 ppm (700)
0–50°C / 32–122°F
±0.1 EC / ±50 ppm (500) / ±70 ppm (700), ±1°C
0.1 EC / 10 ppm, 1°C
Automatic (ATC)
Factory calibrated — manual calibration optional
EC, ppm 500, ppm 700, °C, °F
Backlit LCD with low battery indicator
1 x AAA alkaline (included) — approx. 350 hours
Fully waterproof, auto off, hold reading function
1-year limited warranty
Bluelab, New Zealand
- The pen is only as accurate as the probe is clean. Rinse it under running tap water after every use to stop nutrient salts building up.
- Every two weeks, clean the probe face with a drop of Bluelab Conductivity Probe Cleaner or an unscented cream cleanser like Jif — never scented varieties, the oils contaminate the probe.
- Low readings almost always mean a dirty probe, not a faulty pen. Clean it and retest before assuming anything's wrong.
How to Use It
Pairs Well With
EC tells you how much food is in the water — pH tells you whether the plant can eat it. Run both for the full picture.
Calibration & Probe Care2.77 EC standard solution and probe cleaner keep your readings honest for years.
Water ControlPumps, reservoirs and dosing gear to act on what the pen tells you.
NutrientsBase nutrients and additives — measured feeds beat guesswork every time.
Frequently Asked Questions
Does the Bluelab Conductivity Pen need calibrating before first use?
No. It's factory calibrated and ready to use out of the box. Manual calibration is optional — if you want to check it, clean the probe first, then calibrate in Bluelab 2.77 EC standard solution.
Does it measure pH?
No. This pen measures conductivity (EC/ppm) and temperature only. For pH, pair it with the Bluelab pH PenPlus — the two together cover everything you need to know about your nutrient solution.
Is the pen waterproof?
Yes, fully waterproof — provided the battery cap is fastened down with no gap between cap and body. It will survive a dunk in the reservoir.
Does it read the 540 ppm scale?
No. It reads EC, ppm 500 (TDS) and ppm 700. If your feed chart uses the 540 scale, set the pen to EC and multiply the reading by 540 to convert.
Why is my pen reading low?
Low readings usually mean the probe is contaminated with nutrient salt build-up, not that the pen is faulty. Clean the probe face with Bluelab Conductivity Probe Cleaner or an unscented cream cleanser, rinse, and retest in a known solution.
What battery does it take?
One AAA alkaline battery, included, with around 350 hours of life. Don't use rechargeables — Bluelab specifies alkaline only.
Stop Guessing Your Nutrient Strength
Bluelab accuracy, backed by a 1-year warranty. Free shipping over $499*.