Short version? Get the Bluelab pH Pen and the Bluelab Truncheon. One does pH, one does EC, and both survive being knocked off the bench. Which happens. Watching the pennies? The Essentials pens do the same job for less, or the Aqua Master P110 Pro 2 does pH and EC in one pen for £69 (and its kits save you up to £6). Running a commercial room? That's Hanna GroLine territory. And whatever you buy, look after it. There's a whole section on that below, because it matters more than the badge on the front.
The best pH and EC meters
Bluelab pH Pen
Walk into most grow rooms and there's one of these lying about somewhere. Reads pH and solution temperature, and calibrating it isn't a faff.
- pH and temperature
- Two-point calibration
- Pocket size
- Settles on a reading quickly, as long as you keep the probe wet
- Calibrates with pH 7 and pH 4 buffer
- Spares and care kits are easy to get hold of
Bluelab Truncheon
The big blue stick. Half the reservoirs in the country have had one of these poked in them. No calibrating, you just keep it clean.
- EC, CF, ppm 500 and 700
- Factory calibrated
- Waterproof
- Long enough to stir the tank with (we won't tell)
- Reads EC, CF and both ppm scales, so it'll match whatever your feed chart says
Essentials pH Meter
Swiss-made, one button, batteries already in the box. Does what most home growers need and doesn't pretend to do more.
- One-button use
- Water and drop resistant
- Floats
- Batteries included
- It floats. Drop it in the tank and you can fish it straight back out
- Rebuilt for the relaunch with more consistent calibration
Bluelab Combo Meter
pH, EC and temperature in one handheld, with two separate probes. For anyone who's had enough of juggling.
- pH, EC and temperature
- Two probes
- Portable, no mains
- One unit to carry round the room instead of two pens and a damp cloth
- Calibration steps printed on the back, so no hunting for the manual
Aqua Master P110 Pro 2
pH, EC and temperature in one pen, for roughly a quarter of what the Bluelab Combo costs. Bit of a bargain, that.
- pH, EC and temperature
- Replaceable electrode
- IP67, floats
- AAA batteries
- When the electrode wears out you swap it, not the whole pen
- Nags you to calibrate every 30 days. Someone has to
- The electrode doesn't need storing in solution between uses, which is handy if you're forgetful
Hanna GroLine pH Tester HI-98118
Hanna make lab equipment, and GroLine is that kit built for growers. Not the household name over here that Bluelab is. But go round a few commercial set-ups and you'll see plenty of them, and there are good reasons for that.
- pH and temperature
- Renewable junction
- Auto buffer recognition
- Waterproof
- Renewable junction. When it clogs and the readings start wandering, you clear it instead of binning the probe
- A stability indicator tells you when the reading has actually settled, so nobody's dosing a tank off a number that's still moving
- One or two-point calibration at the press of a button, and it recognises the buffer by itself
- Hanna solutions come with a lot number and an expiry date on every bottle. Handy if you keep proper records
Essentials EC Meter
The budget way to check how strong your feed is. Dip it, give it a stir, and you'll have a steady number in about 20 seconds.
- Automatic temperature compensation
- Protective shroud
- Batteries included
- Temperature compensated, so a cold tank won't throw the reading off
- Slotted shroud keeps the sensor safe while it rattles round your toolbox
Bluelab pH & EC Probe Care Kit
Cleaning, calibration and storage solutions for both probe types. Honestly, most "broken" meters that come back to us are just filthy.
- pH 4 and 7 buffer
- KCl storage
- Cleaning brush
- Sorts out pH pens and EC probes in one box
- Costs a lot less than a new probe
Looking after a pH pen
This bit matters more than which pen you buy. Honestly.
The business end of a pH pen is a thin glass bulb that measures a tiny voltage. Let it dry out, or let it get coated in nutrient gunk, and it starts to drift. Slowly. You won't notice. You'll just keep tipping in pH down to hit a number that isn't real, and a pen that's confidently wrong is worse than no pen at all.
And calibrating a dirty probe doesn't fix it. The meter assumes the glass is clean, so all you're doing is teaching it the wrong answer.
- Rinse it after every use. Clean water, a shake, cap back on. Don't leave it sat in the tank.
- Keep the tip wet with KCl storage solution. A few drops in the cap so the glass never dries out. Never tap water, never RO or distilled. Those pull the salts out of the probe and shorten its life.
- Calibrate regularly. pH 7 first, then pH 4. Fresh buffer in a clean pot each time, and bin it afterwards.
- Clean it when it gets slow. Monthly is a good habit. Soak the tip in probe cleaning solution for 15 to 20 minutes, then let it sit in storage solution for an hour before you trust a reading.
- Know when it's had it. If it still won't calibrate after a proper clean, the probe's worn out. On pens with a replaceable electrode, like the P110 or Hanna's GroLine HI-98115, that's a cheap fix rather than a new pen.
The storage and calibration solutions we stock:
Using a Hanna? Stick with Hanna storage solution and Quick Cal, both from £11.40.
At a glance
Quick refresher. pH tells you whether the plant can actually take the food up. EC tells you how strong the food is. You want both numbers, really.
| Meter | Measures | Calibration | Price |
|---|---|---|---|
 Bluelab pH Pen |
pH, temp | pH 7 and 4 | £84.90 |
 Bluelab Truncheon |
EC, CF, ppm | None needed | £84.90 |
 Essentials pH Meter |
pH | Buffer solution | £58.00 |
 Bluelab Combo Meter |
pH, EC, temp | pH probe only | £262.00 |
 Aqua Master P110 Pro 2 |
pH, EC, temp | pH and EC solutions | From £69.00 |
 Hanna GroLine HI-98118 |
pH, temp | Quick Cal, 1 or 2 point | £99.95 |
 Essentials EC Meter |
EC | Check solution | £55.00 |
 Probe Care Kit |
Upkeep | Includes buffers | £28.00 |
Prices as at October 2026. Check the product page for the live price.
How to choose
- Just starting out? Buy a pH pen first. If the pH is off, the plant can't take up the nutrients, however good your feed is.
- Running coco or hydro? Get the EC meter too. You're feeding every time you water, so strength matters.
- Want everything sorted in one go on a budget? The P110 Pro 2 kit with calibration solution. Pen, fluids, done.
- Running a bigger or commercial room? Hanna GroLine. And if the room's full of pumps and ballasts, the HI-9814 with its pre-amplified probe.
- Whatever you buy, read the pen care bit above. Twice.
More on getting your numbers right in our hydroponic nutrients guide.
Quick answers
Do I really need a pH meter?
If you're mixing your own feed, yes. Drops and strips are fine for a rough idea, but good luck reading the colour once nutrients have tinted the water.
What's the difference between EC and ppm?
Same measurement, different scale. EC is the raw conductivity reading and ppm is a conversion of it. Just make sure your meter and your feed chart are talking the same language, 500 or 700, or the numbers won't line up.
How often should I calibrate?
Check a pH pen in buffer 7 every week or two and calibrate when it's off. The Truncheon doesn't need calibrating at all. Just a clean.
Can I store my pH pen in tap water?
Please don't. Tap, RO and distilled water all slowly pull the life out of a pH probe. A few quid on KCl storage solution saves you buying a new pen.
Why is my pH pen drifting?
Nine times out of ten it's a dirty or dried-out probe. Clean it, give it a good soak in storage solution, then recalibrate. Still wandering about? The probe's probably had its day.
Still stuck? Give us a ring on 020 8686 9643 or email info@thehydrobros.com.
Or pop into the shop for a natter: Unit 12, Progress Business Park, Progress Way, Croydon CR0 4XD.
More grow guides
- Grow tent setup guide
- Grow room extraction: choosing a fan and filter
- Best hydroponic nutrients UK
- Spider mites: identify, treat and prevent
- What pump for FloraFlex drippers?
- How many drippers per plant?
The Hydro Bros Team. We sell this kit and talk growers through it every day in our Croydon shop.
