Short version? If you want pH and EC without buying two pens, and you don't fancy spending £262 on a Bluelab Combo, the Aqua Master P110 Pro 2 is the one we point people at. £69 for the pen. The probe's replaceable. It floats. And the calibration reminder means you can't really claim you forgot. Buy it as a kit with the calibration fluids and you'll save up to £6 on top.
Aqua Master P110 Pro 2
- pH, EC and temperature
- Replaceable electrode
- IP67, floats
- AAA batteries
- 30-day calibration reminder
The numbers
| Measures | pH, EC and temperature (°C or °F) |
| Display | Black screen, white text. Choose 1 or 2 decimal places |
| Power | Standard AAA batteries, included |
| Waterproofing | IP67, and it floats |
| Electrode | Replaceable. Replacement electrode £29.95 |
| Calibration | Arrives calibrated. Reminds you every 30 days |
| Price | £69.00 pen only, kits from £76.95 |
Aqua Master P110 Pro 2 FAQs
Is the Aqua Master P110 Pro 2 any good?
For the money, yes. It reads pH, EC and temperature in one pen for £69, the electrode can be replaced when it wears out, and it's waterproof to IP67. If you need 24/7 monitoring with alarms, it's the wrong tool. For checking a tank by hand it does the job.
P110 Pro 2 or Bluelab Combo Meter?
Both read pH, EC and temperature. The Bluelab Combo is £262 and uses two separate probes on a handheld unit. The P110 Pro 2 is £69 and puts it all in one pen. Most home growers are fine with the P110. Bigger rooms tend to go Bluelab or Hanna.
Does it come calibrated?
Yes. It's calibrated out of the box and the batteries are in. You'll want to recalibrate after about a month, and the pen will remind you.
What calibration solution do I need?
pH 4, pH 7 and EC solution. The Aqua Master 4-pack covers all three plus KCl storage solution, or get it bundled with the pen and save.
Can I replace the probe?
Yes, and it's one of the best things about it. A replacement electrode is £29.95, which is a lot cheaper than a new pen.
Do I have to store it in solution?
Aqua Master say the electrode doesn't need storing in solution between uses. Just never leave it sat in distilled water.
Why won't my EC reading go back to zero?
Usually residue on the sensor. Dip the electrode in ethyl alcohol and give it a gentle shake for 5 to 10 seconds, then rinse.
Is it waterproof?
It's IP67 and it floats, so a dunk in the tank won't kill it. Still not something to leave in there, though.
What it does well
It's one pen. That's most of the appeal. Dip it, read pH, press MODE, read EC. No second meter to fish out of your pocket with wet hands.
The replaceable electrode is the bit we'd shout about, though. Probes wear out. On a lot of cheaper pens that means the whole thing goes in the bin. Here you swap in a replacement electrode for £29.95 and carry on.
- Floats, so a slip over the tank isn't the end of the world
- Runs on normal AAA batteries rather than fiddly button cells
- Nags you to calibrate every 30 days. Someone has to
- Rubber grip and a cord on the cap, so the cap doesn't wander off
Where it falls short
Good fit if you...
- want pH and EC in one pen on a budget
- run a tent or a small room
- are happy to calibrate once a month
Look elsewhere if you...
- need round-the-clock monitoring with alarms
- run a big commercial room full of pumps and ballasts
- never, ever calibrate anything
Which version to buy
You'll need calibration fluid whatever happens, so the kits make sense. We've checked these against buying each bit separately.
| Option | Price | Saving |
|---|---|---|
| P110 Pro 2 pen only | £69.00 | n/a |
| Pen + pH up and pH down + pipettes | £76.95 | £4.04 |
| Pen + Aqua Master calibration 4-pack + pipettes | £82.95 | £4.05 |
| Pen + 4-pack + pH up and down + pipettes | £92.95 | £6.04 |
| Replacement electrode | £29.95 | n/a |
The 4-pack is pH 4, pH 7, EC and KCl storage solution. Prices as at October 2026.
Starting from scratch? Get the full kit. Everything's in the box and you won't be back next week for buffer.
How to use it
- Pull the cap off and give the electrode a gentle rinse. Dry it off.
- Switch it on and stand it upright in your solution, up to the edge of the electrode. Give it a gentle stir.
- Wait a few seconds for the number to settle.
- Press MODE to flip between pH and EC. C/F swaps the temperature units.
- Rinse it, cap it, switch it off. Done.
Looking after it
A meter is only as good as its last calibration. Once a month, minimum, and any time the readings look a bit odd.
- Calibrate with warm fluid. 25°C, as above. Cold buffer throws it out.
- Watch for bubbles. Air bubbles round the electrode during calibration will mess with the result. Give it a tap.
- Never store it in distilled water. It shortens the electrode's life. The probe doesn't need to sit in solution between uses, but a few drops of KCl in the cap won't hurt.
- EC won't drop to zero? Aqua Master's fix is a quick swish in ethyl alcohol for 5 to 10 seconds.
- Still won't behave after all that? The electrode has probably had its day. Swap it for £29.95.
How it stacks up
| Meter | Measures | Replaceable probe | Price |
|---|---|---|---|
| Aqua Master P110 Pro 2 | pH, EC, temp | Yes | £69.00 |
| Essentials pH + EC | pH and EC (two pens) | No | £113.00 |
| Hanna GroLine HI-98118 | pH, temp | Renewable junction | £99.95 |
| Bluelab pH Pen + Truncheon | pH and EC (two pens) | No | £169.80 |
| Bluelab Combo Meter | pH, EC, temp | pH probe | £262.00 |
On price per reading it's hard to argue with. But if you'd rather have the brand most growers already know, the full rundown is in 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
- Best carbon filters for grow tents
- Grow tent setup guide
- Best hydroponic nutrients UK
The Hydro Bros Team. We sell this kit and talk growers through it every day in our Croydon shop.
