Apera GroStar® GS4-P 6-in-1 Combo Pen Tester Kit (Gen II) — pH, EC, ppm, ORP & Temperature for Growers
The Apera GroStar GS4-P Gen II is the most comprehensive all-in-one pen tester kit for serious growers. It measures pH, EC, 500 ppm (NaCl), 700 ppm (KCl), ORP (mV), and temperature — six parameters, two replaceable probes, one streamlined kit. Monitor nutrient strength, acidity, and oxidation-reduction potential without juggling multiple meters.
Key Features
-
6-in-1 Measurement — pH, EC, 500 ppm, 700 ppm, ORP, and temperature from a single kit; the most complete grower monitoring solution in a pen form factor
-
Dual Replaceable Probes
-
pH/EC Combo Probe — Double-junction pH sensor + titanium conductivity sensor for fast, reliable, long-life readings
-
ORP Probe — Replaceable double-junction platinum ORP probe; plug in and the tester auto-switches to ORP measurement mode
-
Auto ORP Mode Switching — Connect the ORP probe and the meter automatically enters ORP mode — no manual mode selection required
-
TruRead™ Measurement Mode — Measure across multiple reservoir zones or plant sites and automatically display average, minimum, and maximum values for comprehensive grow monitoring
-
Dual ppm Scales — Supports both 500 ppm (NaCl) and 700 ppm (KCl) for universal compatibility with any nutrient line or feeding chart
-
2-Point Automatic Calibration — Simple workflow with electrode condition display for real-time probe health monitoring
-
3-Color Backlit LCD — Clear readings in any lighting; color-coded by mode for instant status recognition
Measurements at a Glance
-
pH — Nutrient solution acidity/alkalinity
-
EC — Electrical conductivity (nutrient strength)
-
500 ppm — NaCl conversion scale
-
700 ppm — KCl conversion scale
-
ORP (mV) — Oxidation-reduction potential (water sanitation/redox monitoring)
-
Temperature — °C / °F
Applications
Hydroponics, aquaponics, cannabis cultivation, greenhouse growing, nutrient solution monitoring, reservoir management, pool & spa ORP monitoring, water treatment, and general water quality testing.
Why GroStar GS4-P?
The GS4-P adds ORP monitoring to the full GS4 feature set — critical for growers using oxidizing agents (hydrogen peroxide, chlorine, ozone) to sanitize reservoirs. With auto probe-switching, dual replaceable probes, dual ppm scales, and TruRead™ multi-point averaging, it’s the most grower-intelligent 6-in-1 pen kit available.
