HM Digital Pro Series COM-300 pH/TDS/EC/Temp Pen Meter - Waterproof IP-67

Four Water Readings in One Pen - IP-67 Waterproof

Testing nutrient solution with separate tools slows down every reservoir check. This pen meter measures pH, EC, TDS and temperature in a single unit, so you can check a hydroponic system without switching devices. The housing is rated IP-67 waterproof, and the sensor is replaceable when it wears out.

Sold as a single unit, this meter suits home growers and small indoor setups, and it also works as a backup or spot-check tool for commercial cultivation teams who test water across several reservoirs.

Key Features & Benefits

• Four measurements in one pen — check pH, EC, TDS and temperature without carrying several meters.
• IP-67 waterproof housing — rinse it off and use it around wet reservoirs with less worry.
• Replaceable sensor (model SP-C3) — swap the sensor instead of replacing the whole meter.
• Wide measuring ranges — pH 0 – 14, EC 0 – 9990 µS or 0 – 9.99 mS, and temperature 0-55 °C (32-130 °F).
• Kit included — comes with a translucent cap, 2 AAA alkaline batteries, pH 4 & 7 calibration solutions, pH storage solution and a lanyard.

Who Should Use HM Digital Pro Series Pen Meter

Growers who manage nutrient solution in hydroponic systems, and anyone who wants a handheld tool for routine water checks during vegetative growth and flowering.

About HM Digital Pro Series Pen Meter

HM Digital makes water-testing instruments. This Pro Series pen meter (COM-300) combines pH, TDS, EC and temperature measurement. It reads TDS in ppm on two scales: 0 – 8560 ppm on the 0.7 scale and 0 – 5000 ppm on the 0.5 scale. Its stated accuracy is +/- 2%.

Frequently Asked Questions

Q: What does this meter measure?
A: It measures pH, EC, TDS and temperature. That covers the main checks for a hydroponic nutrient solution in one pen.

Q: Is it waterproof?
A: The housing has an IP-67 rating. This means it is built to resist water exposure during normal use around reservoirs.

Q: What comes in the box?
A: You get a translucent cap, 2 AAA alkaline batteries, pH 4 & 7 calibration solutions, pH storage solution and a lanyard.

Q: What is the difference between EC and TDS?
A: EC measures how well a solution conducts electricity, which indicates how much dissolved material it holds. TDS estimates the total dissolved solids in ppm, and it depends on which scale is used.

Q: Can I replace the sensor?
A: Yes. The meter uses a replaceable sensor, model SP-C3, so you do not need to replace the whole pen.

Q: What batteries does it use?
A: It uses 2 AAA batteries, and two alkaline cells are included.