BlueLab Multimedia pH meter

One handheld meter for your nutrient solution and your medium. The Bluelab Leap probe is included, so you measure directly in soil, coco and rockwool without buying anything extra.

The Bluelab Multimedia pH Meter reads from 0.0 to 14.0 pH to an accuracy of 0.1, and calibrates on two points at the push of a button. The screen confirms a successful calibration; after thirty days that confirmation disappears as a signal that it is time again.

Why this is called a multimedia meter

The difference from an ordinary pH pen is the probe on the end of it, and that decides where you can measure.

An ordinary pH pen has a thin, rounded glass membrane. It is built to hang in liquid: your reservoir, your source water, your nutrient solution. Push one into soil or rockwool and it reads unreliably and eventually breaks.

This meter comes with the Bluelab Leap probe in the box, and that is built for both:

• A hardened spear tip that takes being pushed into a medium, rather than a vulnerable bulb.
• A double junction rather than a single one. That second junction keeps contamination further from the sensing element, which matters far more in a medium than in clean water.
• A two metre cable, so you can reach a pot at the back of your room without moving everything.

That lets you measure where it actually counts: in the root zone. What you pour into your reservoir and what your roots meet are two different things, and the gap between them is exactly where problems start.

The probe sits on a BNC connector and can be replaced on its own. That matters more than it sounds: the probe is the consumable, the meter is not. When the probe gives up after a few years, you replace it and keep the meter.

What kills a pH electrode, and how to avoid it

A pH probe is a wear part, and most die sooner than they need to. Four causes, in order of how often they happen.

Drying out. By far the most important. The glass membrane only measures while hydrated. A probe left dry in a drawer for a week is sluggish when you find it, and sometimes beyond saving. Store it in KCl storage solution, in the cap it came with.

Storing in deionised water. This feels clean and is precisely wrong. Pure water is ion-poor and therefore pulls ions out of the membrane. You slowly rinse away the thing that makes the measurement possible. Rinsing in clean water is fine; storing is not.

Fouling. Nutrient salts and biofilm build a film on the glass. The result is not that the meter stops, but that it slows down and drifts further and further. Clean it with the proper cleaning solution, never with detergent or an abrasive.

Mechanical damage. Even a hardened tip is still glass. In a medium with perlite or coarse coco, push it in gently rather than forcing it.

The pattern in all four: a dying probe gives no error. It gives tidy numbers that are further and further out. Which is why calibration is not a formality but your only check. When a meter can no longer be brought back to a known value, that is the moment you find out.

Measuring in a medium

Slightly different from liquid, and it decides how much your reading is worth:

• Measure in moist medium. Bone-dry soil gives no usable value; measure shortly after watering, or wet the spot.
• Push it in gently until the tip sits in the root zone, not just the top layer.
• Give it a moment. The value drifts for a few seconds before it settles.
• Rinse after use with clean water and put it back in the cap with KCl.

Technical Specifications:

• pH range: 0.0 to 14.0 pH
• Resolution: 0.1 pH
• Accuracy: ± 0.1 pH
• Included: Bluelab Leap pH probe with hardened spear tip
• Probe cable length: 2 metres
• Probe connection: BNC, probe separately replaceable
• Suits: nutrient solution, soil, coco, rockwool and potting mix
• Calibration: two-point (pH 4 and 7) at the push of a button
• Calibration indicator: on-screen confirmation, expires after 30 days
• Display: backlit LCD
• Other: low-battery indicator, automatic shut-off
• Battery: 2 x AAA alkaline (included)

Frequently asked questions

Is the Leap probe included?
Yes. The Leap probe ships with this meter; that is exactly what makes it a multimedia meter. You can measure in your reservoir and in your medium straight away.

Can I also measure in my nutrient tank with it?
Yes. The Leap probe works just as well in liquid as in a medium, so you do not need a second probe.

What does the BNC connection mean for me?
That you can replace the probe rather than the whole meter. A probe is a wear part; a meter is not. The same connection is on the Bluelab Guardian and the Combo Meter, so probes are interchangeable within that range.

Why does the calibration indicator disappear after thirty days?
To stop you trusting a meter last adjusted months ago. An electrode drifts gradually, and you cannot see that in the numbers.

Can I leave it in a tank for continuous measurement?
No, this is a handheld meter for spot readings. For continuous measurement with an alarm on deviation, a monitor such as the Bluelab Guardian is the tool.

What else do I need?
Calibration solution pH 4.01 and pH 7.01, and KCl storage solution for the cap. Cleaning solution extends the probe's life considerably.