Bluelab Combo meter Plus PH / EC / temperature

The Combo Meter with a Leap probe in place of the standard pH probe. That lets you read not just your reservoir, but directly in soil, coco and rockwool.

The Bluelab Combo Meter Plus reads pH, EC and temperature through two probes on two-metre cables. Range 0.0 to 14.0 pH and 0.0 to 9.9 EC, both accurate to 0.1, with CF as an extra scale. Five-year warranty on the meter.

What the Plus adds

The difference from the ordinary Combo Meter sits entirely in the pH probe, and it is a bigger difference than the name suggests.

An ordinary pH probe is built to hang in liquid. The tip is thin glass, made for water. A growing medium is abrasive and uneven, and there such a probe either breaks or reads unreliably because there is too little contact between glass and substrate.

The Leap probe is made for both and has a hardened spear tip, so it takes being pushed into a medium and settles on a stable value faster. That makes this meter two instruments in one: you read your nutrient solution before watering and what is actually sitting in the pot.

The second is where most of the surprises are. A plant takes up water faster than salt, so what remains in the medium concentrates with every watering. You water carefully at 6.0 and the pH in the pot slowly drifts. Usually upwards, towards the region where iron becomes unreachable. Your reservoir shows you none of that.

Technical Specifications:

• Range: 0.0 to 14.0 pH · 0.0 to 9.9 EC · 99 CF
• Resolution: 0.1 pH · 0.1 EC · 1 CF
• Accuracy: ± 0.1 pH · ± 0.1 EC
• Calibration: pH at 3 points (4, 7 and 10); EC not required
• Probes: Bluelab Leap pH probe with hardened spear tip (replaceable) and conductivity probe
• Media: nutrient solution, soil, rockwool, coco and potting mixes
• Cables: 2 metres
• Power: 2 x AAA battery (included)
• Warranty: 5 years on the meter, ½ year on the probes

Frequently asked questions

Is the Plus worth the price difference?
If you grow in soil or coco: yes, because you measure where your plant is rather than only what you pour in. If you run a recirculating hydroponic system where the reservoir is the root zone, the Leap probe adds little.

Can I buy the Leap probe separately for my ordinary Combo Meter?
Yes. It has a BNC connector and fits any Bluelab meter with that fitting. Always recalibrate after swapping.

Do I measure differently in a medium than in water?
Yes. Measure in moist medium, at root level, not right beside a dripper, and rinse the tip between pots.

Does the EC probe really never need calibrating?
Correct. It measures between two fixed electrodes and does not drift. It does need keeping clean; salt build-up is the only thing that affects it.