Bluelab Combo Meter (All In One EC + pH)

What does the Bluelab Combo Meter measure?

The Bluelab Combo Meter is a 3-in-1 handheld device that measures pH, electrical conductivity (EC/ppm), and temperature in nutrient solutions. It includes automatic temperature compensation (ATC) for accurate readings in varying conditions, and you can view temperature in °C or °F.

Should I use EC, CF, or ppm on the Bluelab Combo Meter?

EC is the most universal and reliable measurement for nutrient strength. CF is a scaled version of EC, while ppm 500 and 700 are conversions. Use ppm if your feeding chart uses it, but EC is best for comparing across systems.

What types of grows can I use the Bluelab Combo Meter for?

It’s ideal for hydroponics, coco, soil, and nutrient reservoirs. You can also test runoff and water sources. While it works in aquariums or ponds, it’s designed for grow environments. Organic nutrients may require more frequent cleaning.

Does the Bluelab Combo Meter need calibration?

Only the pH probe needs calibration. Perform a 2-point calibration using pH 7.0 and 4.0 buffers. The meter reminds you when it’s time to calibrate. Calibrate monthly—or more often if you're testing daily or using organics.

What’s included and how do the probes work?

The meter comes with a replaceable pH probe (BNC connection) and a combined conductivity/temperature probe. The pH probe uses a double-junction design for durability. All probes connect via long cables for flexible use.

What kind of batteries does the Combo Meter use?

It runs on 2 × AAA batteries, with a low battery indicator and auto-off function to conserve power. Low battery can cause inaccurate readings, so swap them early if things look off.

How do I take accurate readings with the Bluelab Combo Meter?

Use a well-mixed solution, avoid air bubbles near the probes, and let readings settle. Test in a circulating zone—not near an air stone or dosing outlet. Rinse probes between tests to avoid contamination. Sample cups work well for multiple systems.

How do I store and clean the Bluelab Combo Meter probes?

Always store the pH probe in KCl storage solution—not plain water. Clean the pH probe gently and recalibrate after. Clean the EC probe by removing buildup and rinsing well. Dirty probes are a common cause of reading drift.

What should I do if the readings seem wrong?

Check battery level, probe cleanliness, calibration status, and sample mixing. “Err” messages or unstable readings often point to calibration issues or air bubbles. If problems persist, recalibrate or replace the probe if needed.

How do I replace the pH probe on the Bluelab Combo Meter?

The pH probe is easy to swap via the BNC connector. After replacement, calibrate with fresh pH 7 and 4 buffers. The Combo Meter is compatible with other Bluelab pH probes, including specialty options.

What’s the best way to mix and measure nutrients?

Fully mix nutrients first, then check and adjust EC. Adjust pH last, stir again, then recheck. Don’t test straight pH Up/Down—concentrates can damage probes. Always test the final mixed solution.

Why does pH drift after adjusting, even with this meter?

pH readings may change as the solution stabilizes and mixes fully. Always allow time for proper circulation before trusting final readings—especially in larger tanks or after dosing.

Is the Bluelab Combo Meter good for beginners?

Yes—it’s user-friendly and accurate, as long as you calibrate regularly and store the pH probe correctly. Neglecting these basics is the most common mistake and leads to unreliable readings.