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HM Digital Electrode Sonde EC for COM-100
The HM Digital Electrode Probe EC for COM-100 is the original SP-C1 replacement sensor for the HM Digital COM-100 EC/TDS/Temperature combo meter. Extended exposure to concentrated nutrient solutions causes mineral deposits on the stainless steel sensing pins, progressively degrading measurement accuracy beyond what recalibration can correct. This replacement probe restores factory-level precision in under five minutes with no tools required. The sensor measures electrical conductivity and temperature simultaneously, enabling automatic temperature compensation across the full operating range. Constructed from chemical-resistant ABS housing with stainless steel electrodes. Calibrate with a known EC standard solution after installation. Order from plantandflower.be with fast delivery across Belgium.
HM Digital EC Replacement Probe for COM-100 – Restore Measurement Accuracy
Accurate EC measurement is the foundation of precision nutrient management. The HM Digital COM-100 is a professional-grade EC/TDS/Temperature meter widely used in hydroponic cultivation, but its sensor has a finite operational lifespan. Mineral deposits from nutrient solutions gradually coat the stainless steel sensing pins, creating a resistive layer that systematically skews readings. When calibration no longer compensates for this drift, sensor replacement is the only path back to reliable data. This original SP-C1 replacement probe is available from our pH/EC control section.
SP-C1 sensor specifications and compatibility
The replacement probe is engineered exclusively for the HM Digital COM-100 meter. It measures both electrical conductivity and temperature, feeding data to the meter's processor for real-time automatic temperature compensation. The COM-100 then converts raw conductivity readings into the user's preferred scale — µS/cm, mS/cm, or TDS in ppm using either NaCl (0.5 factor) or 442 (0.7 factor) conversion. The probe housing is constructed from chemical-resistant ABS plastic with precision-machined stainless steel sensing pins optimised for rapid response time.
- Model: SP-C1 — original HM Digital replacement part, not a third-party alternative.
- Measurements: electrical conductivity (EC), total dissolved solids (TDS) via conversion, and temperature.
- Construction: ABS housing with stainless steel electrode pins resistant to common hydroponic nutrient formulations.
- Installation: tool-free snap connection — remove old probe, attach new probe, calibrate.
Diagnosing a failing EC sensor
Sensor degradation manifests through several measurable symptoms. Readings take progressively longer to stabilise — values oscillate for ten seconds or more before settling. Calibration with EC 1.413 standard solution fails to reach target or requires excessive trim adjustment. Repeat measurements in the same solution return inconsistent values. Visible mineral deposits persist on sensing pins despite cleaning. These indicators confirm that the electrode surface has degraded beyond recoverable condition and replacement is the cost-effective solution versus purchasing an entirely new meter.
Post-installation calibration protocol
Every new sensor requires calibration before use — manufacturing tolerances create minor variations between individual probes that calibration corrects. Power off the COM-100, disconnect the old sensor and attach the SP-C1 until it clicks securely. Power on and enter calibration mode. Use fresh, uncontaminated EC standard solution at room temperature. For maximum accuracy across the full measurement range, verify the calibration point against a second reference such as EC 2.76 standard. After calibration, rinse the probe with clean water and replace the protective cap. Establish a maintenance routine: rinse after every measurement, clean with electrode cleaning solution monthly, and recalibrate at least every two weeks during active growing periods.
Order the HM Digital EC Replacement Probe for COM-100 from plantandflower.be with fast shipping across Belgium. Protect your instrumentation investment at a fraction of full meter replacement cost.
Is the SP-C1 probe compatible with other HM Digital meters?
The SP-C1 is designed exclusively for the HM Digital COM-100 EC/TDS/Temperature combo meter. It is not compatible with other HM Digital models or EC meters from other manufacturers. Always verify your meter model before ordering a replacement probe.
How long does a COM-100 EC probe last in hydroponic use?
With daily use in nutrient solutions, expect six to twelve months of reliable service life. Consistent rinsing after every measurement and monthly cleaning with electrode cleaning solution extends this period. Replace when calibration consistently fails or readings become unstable.
Do I need to recalibrate after installing the new EC probe?
Calibration after probe replacement is mandatory. Each sensor has slight manufacturing variations that calibration compensates for. Use fresh EC 1.413 µS/cm standard solution at room temperature for optimal accuracy.
What causes EC probe degradation in grow room environments?
Concentrated nutrient solutions deposit mineral salts on the stainless steel sensing pins over time. These deposits alter the effective electrode surface area and geometry, changing the electrical resistance between pins and producing inaccurate conductivity readings that calibration cannot fully correct.