Bluelab Combo Meter | pH EC Temperature Meter Hydroponics Australia

Bluelab Combo Meter | pH, EC and Temperature Meter for Hydroponics Australia

The Bluelab Combo Meter reads pH, EC and temperature at the same time, so you get the full picture of your nutrient solution in one measurement instead of switching between instruments. It's a long-standing default for growers running recirculating systems, DWC, NFT or coco feed programs, and it's made in New Zealand with a five-year warranty behind the meter body.

Why Measuring All Three Together Matters

pH, EC and temperature aren't independent. The same solution reads differently at 18 degrees than at 26, so an EC figure taken without knowing the temperature can send you chasing a strength problem that doesn't exist. A pH reading taken the same way can push you into correcting in the wrong direction. Automatic Temperature Compensation handles this, so the EC you see reflects actual nutrient concentration rather than a temperature-skewed number.

That matters more in an Australian grow room than in most places. A Melbourne reservoir in summer can run 8 to 10 degrees warmer than the same room in winter, and that changes how nutrients behave in solution. Our guide on cooling a grow tent through summer covers what to do once temperature is the problem rather than the measurement.

What It Measures

pH on a 0.0 to 14.0 scale at 0.1 resolution. The double-junction probe resists the reference contamination that kills single-junction probes early, and it connects by standard BNC, so when it wears out you replace the probe rather than the meter. That's the main reason this unit stays in service for years.

EC in EC (mS/cm), CF, ppm 500 or ppm 700, selectable. This matters more than it sounds. North American feed charts usually run ppm 500 while Australian and European charts use EC or CF, so being able to match your meter to your chart removes a real source of error when you switch nutrient brands. Our EC targets guide covers the numbers by crop and stage.

Temperature in Celsius or Fahrenheit, read by the same probe as EC. Knowing reservoir temperature alongside EC tells you whether a climbing EC is plants drinking water faster than nutrient, which concentrates what's left, or a genuine change in solution strength. Those need opposite responses.

Getting Accurate Readings

Infrequent calibration causes most inconsistent readings on this meter. The pH probe drifts, and it drifts faster in a warm room where biological activity in stored calibration solution shifts its reference point. Calibrate against fresh pH 4.0 and pH 7.0 solution at least weekly during an active grow, and always after the probe has been stored dry.

Store the probe tip in KCl storage solution between uses. A dried-out double-junction membrane is not recoverable. Bluelab calibration sachets in pH 4.0, pH 7.0 and EC 2.77 mS/cm give you measured single-use portions, which removes the contamination risk of dipping into the same bottle repeatedly. If your readings are right and the plants still look wrong, our nutrient deficiency chart covers what to check next.

Technical Specifications

• Measurements: pH, EC, temperature (simultaneous)
• pH probe: Replaceable double-junction, BNC connection
• EC units: EC (mS/cm), CF, ppm 500 (TDS), ppm 700 (selectable)
• Temperature units: Celsius and Fahrenheit (selectable)
• Temperature compensation: Automatic (ATC)
• Display: Backlit LCD
• Calibration: 2-point pH (4.0 and 7.0). The EC probe is factory calibrated and needs none.
• Cable length: 2 metres
• Power: 2 x AAA batteries (included)
• Origin: Made in New Zealand
• Warranty: 5 years on the meter. Probes carry a shorter separate warranty.
• Shipping Weight: 0.9 kg
• Shipping: Free to VIC, NSW, QLD, SA and ACT

The Bluelab Combo Meter is a New Zealand made 3-in-1 pH, EC and temperature meter with a replaceable probe, built for growers who want one instrument to manage a full feed program.

Frequently Asked Questions

How often should I calibrate it?

Calibrate the pH probe at least weekly during an active grow. If you're adjusting pH daily and the numbers look inconsistent, calibrate before you touch the nutrient solution. A drifted probe is the most common cause of pH problems that won't respond to correction.

Does the EC probe need calibrating too?

No. The conductivity and temperature probe is calibrated at manufacture and locked in, so routine maintenance is pH only. The EC 2.77 mS/cm sachet is available if you want to verify it's still reading true, but it isn't part of the normal routine.

What's the difference between EC and ppm?

EC in millisiemens per centimetre is the base measurement. Ppm 500 and ppm 700 are conversions using different factors, so the same solution gives different ppm numbers on each. Match the scale to your feed chart and stay on it.

How long does the pH probe last?

Typically 12 to 18 months with regular use and proper KCl storage. When readings become slow to settle or stay wrong after fresh calibration, the probe is done. Replacement probes fit the standard BNC connection without tools, which is why the meter itself lasts far longer.

Is it waterproof?

The probes are made for immersion in nutrient solution. The meter body is splash resistant and should not be submerged. The 2 metre cable is there so the meter sits outside the reservoir while the probes go in.

What pH should I be running?

For most hydroponic systems, 5.5 to 6.5, targeting 5.8 to 6.2 for the broadest nutrient availability. Coco sits at 5.8 to 6.2 and indoor soil at 6.0 to 7.0. Our guide on why pH keeps dropping covers managing it in Australian conditions.

Does it qualify for free shipping?

Yes. At $424.95 and 0.9kg it clears the $150 threshold and sits well under the 3kg cap, so it ships free to VIC, NSW, QLD, SA and ACT. WA, NT, Tasmania and remote areas are quoted separately.