Short version? The Bluelab Truncheon is the EC meter we hand to coco and hydro growers who can't be doing with calibration. £84.90. It comes factory calibrated, it's fully waterproof, it runs on AA batteries and there isn't a single button on it. Keep the probe clean and that's your maintenance. It only reads feed strength, mind, so you'll still want a pH pen next to it. There's no kit bundle for this one, so no saving to tell you about.
Bluelab Truncheon Nutrient Meter
- EC, CF, ppm 500 and 700
- No calibration needed
- Fully waterproof
- Auto temperature compensation
- AA batteries
- 5-year warranty
The numbers
| Measures | EC, CF, ppm 500 scale and ppm 700 scale |
| Calibration | None. Factory calibrated, you just keep the probe clean |
| Temperature | Automatic temperature compensation |
| Display | LED indicator lights |
| Controls | No buttons or switches |
| Power | AA batteries, with auto power off |
| Waterproofing | Fully waterproof |
| Warranty | 5 years from the manufacturer |
| Made in | Designed and manufactured in New Zealand |
| Price | £84.90 |
Bluelab Truncheon FAQs
Is the Bluelab Truncheon any good?
Yes, if all you need is feed strength. It reads EC, CF and both ppm scales, needs no calibrating, it's fully waterproof and comes with a 5-year warranty. It won't read pH, so budget for a pH pen as well.
Bluelab Truncheon or Bluelab Commercial Truncheon?
Most growers are fine with the standard Truncheon at £84.90. If you run heavy feeds, the Commercial Truncheon at £99.00 reads all the way up to 6.0 EC. Same no-calibration design, same waterproof body, but it takes AAA batteries rather than AA.
Does the Bluelab Truncheon need calibrating?
No. It's factory calibrated and stays accurate as long as the probe is clean. If you want to check it, dip it in 2.77 EC standard solution after cleaning. Bluelab say it should read within 0.1 of 2.8 EC.
How do I clean a Bluelab Truncheon probe?
Twist the shroud 90 degrees and pull it off. Put a drop or two of Bluelab Conductivity Probe Cleaner on the probe face, rub it firmly with the chamois, then rinse under the tap. When water sits as an even film rather than beading up, it's clean. Everything you need is in the Bluelab EC Probe Care Kit.
Why is my Bluelab Truncheon reading wrong?
Nearly always a dirty probe. Nutrient salts build up on the sensor and the reading goes slow, jumpy or just off. Give it a proper clean, check it against standard solution, and only then start blaming the meter.
Does the Bluelab Truncheon measure pH?
No, it only measures conductivity: EC, CF and ppm. Pair it with the Bluelab pH Pen (£84.90) for both numbers.
What batteries does the Bluelab Truncheon take?
Standard AA batteries. It switches itself off to save battery.
Is the Bluelab Truncheon waterproof?
Yes, it's fully waterproof and built for use around reservoirs and mixing tanks. Dropping it in the tank isn't the end of the world.
What it does well
No calibrating. That's the headline, really. Most EC pens want regular fiddling with standard solution or they start telling porkies. The Truncheon comes calibrated from the factory and Bluelab's line is that a clean probe is all it needs.
And it's long. Long enough to stir the reservoir while you take the reading, which sounds daft until you've done it a few times and realised you've stopped reaching for a separate stick.
No buttons either. Pop it in the solution, read the lights, done.
- Reads EC, CF and both ppm scales, so it'll match whatever your feed chart uses
- Automatic temperature compensation, so a cold tank won't throw the number out
- Fully waterproof, which is just as well round a reservoir
- Normal AA batteries and auto power off
- 5-year warranty from Bluelab
Where it falls short
Good fit if you...
- feed coco or hydro and check strength every time you mix
- can't be bothered with calibration
- want something tough enough for a busy grow room
Look elsewhere if you...
- want pH and EC in one tool
- run very strong feeds as standard
- want readings logged round the clock
Which version to buy
There's just the one Truncheon and no bundle, so this is really about which meter suits your feed.
| Option | Price | Best for |
|---|---|---|
| Bluelab Truncheon | £84.90 | Most home growers on coco or hydro |
| Bluelab Commercial Truncheon | £99.00 | Heavy feeds, up to 6.0 EC |
| Truncheon + Bluelab pH Pen | £169.80 | Both numbers from two dedicated meters (bought separately) |
Prices as at November 2026.
Starting from scratch? Truncheon plus pH pen, and chuck an EC Probe Care Kit in the basket while you're at it.
How to use it
- Mix your nutrient solution as normal.
- Pop the probe end into the solution. There's nothing to switch on or press.
- Give the tank a stir with it if you're still mixing. That's what the long body is for.
- Read the strength off the LED lights. Temperature compensation is automatic.
- Take it out and leave it. It powers itself off.
Looking after it
This is the bit people skip. Don't. A Truncheon with salt build-up on the probe will happily show you the wrong number.
- Clean it once a month. That's Bluelab's own recommendation for normal use.
- Clean it sooner if it plays up. Slow to settle, jumping about, or a reading that suddenly looks off. Clean first, panic later.
- Do it properly. Shroud off with a 90 degree twist, a drop or two of probe cleaner, a firm rub with the chamois, then rinse under running tap water. You're after an even film of water on the probe face, not beads.
- Check it after. Shroud back on and test it in 2.77 EC standard solution. Within 0.1 of 2.8 EC and you're good. If not, clean it again.
The EC Probe Care Kit has probe cleaner, a chamois, a decanter and two sachets of 2.77 EC standard solution. Got a pH pen too? The pH & EC kit covers both.
How it stacks up
| Meter | Measures | Calibration | Price |
|---|---|---|---|
| Bluelab Truncheon | EC, CF, ppm 500 and 700 | None needed | £84.90 |
| Bluelab Commercial Truncheon | EC up to 6.0, CF, ppm 500 and 700 | None needed | £99.00 |
| Hanna GroLine HI-98318 | EC, TDS, temp | Automatic single point | £99.95 |
| Essentials EC Meter | EC | Every 10 measurements | £55.00 |
| Aqua Master P110 Pro 2 | pH, EC, temp | Every 30 days | £69.00 pen only |
Prices as at November 2026.
The Essentials is cheaper, but it's splashproof rather than waterproof and wants calibrating often. The Hanna adds a temperature readout. The Truncheon just gets on with it. Want the whole field side by side? Have a read of our best pH and EC meters guide.
Got a question about it? Give us a ring on 020 8686 9643 or email info@thehydrobros.com.
Or pop into the shop and have a look at one: Unit 12, Progress Business Park, Progress Way, Croydon CR0 4XD.
More grow guides
- Best pH and EC meters for growers
- Aqua Master P110 Pro 2: a closer look
- Best coco coir and coco mixes
- CANNA Coco A&B: a closer look
- Best root stimulators for growers
- Best hydroponic nutrients UK
The Hydro Bros Team. We sell this kit and talk growers through it every day in our Croydon shop.
