DFRobot Electrical Conductivity (EC) Sensor Selection Guide

This guide provides a side-by-side comparison and selection analysis for 5 core Electrical Conductivity (EC) sensors from DFRobot, helping you quickly identify the most suitable product based on measurement range (K-value), application scenario (industrial/laboratory), and system architecture (Analog/RS485).

(Note: 1 ms/cm = 1000 μs/cm)

Selection Decision Tree: Ask Yourself 3 Questions

Q1: What kind of water are you measuring? (Determines K-value)

• Normal Water (Tap water, hydroponic nutrients, freshwater aquaculture): Choose K=1 probes.
• High-Concentration Water (Seawater, wastewater, brine): Choose K=10 probes.

Q2: Will the probe be submerged in water long-term? (Determines Grade)

• Occasional Measurement (Sampling): Choose Laboratory Grade. High cost-performance, but MUST NOT be submerged long-term, otherwise the platinum black layer will be permanently damaged.
• 24/7 Continuous Monitoring: You MUST choose Industrial Grade. IP68 waterproof, corrosion-resistant, and supports long-term immersion.

Q3: What is your mainboard / system architecture? (Determines Signal Interface)

• Arduino / Raspberry Pi / Maker DIY Projects: Choose Analog (Gravity) Interface. Supports 3.3V~5V wide voltage, plug-and-play, with ready-to-use code libraries.
• PLC / Industrial Gateways / Large-scale Agricultural IoT: Choose RS485 Interface. Supports 10~30V industrial power supply, strong anti-interference, long transmission distance, and uses standard ModBus-RTU protocol.

Detailed Product Reviews & Target Audience

🟢 Maker/Lab Basic Models (Analog)

1. Gravity: Lab Grade Analog EC V2 (K=1) - DFR0300 ($69.90)

• Positioning: The most cost-effective entry-level freshwater measurement kit.
• Pros: Affordable, plug-and-play, hardware-filtered stable data.
• Cons: Limited probe lifespan (cannot be submerged long-term); lacks a temperature sensor, requires an external DS18B20 for temperature compensation.
• Ideal For: DIY players on a budget, student projects, short-term indoor hydroponic sampling.

2. Gravity: Lab Grade Analog EC (K=10) - DFR0300-H ($79.90)

• Positioning: Affordable sampling solution for seawater and high-salt wastewater.
• Pros: Large measurement range (up to 100 ms/cm), easy single-point calibration.
• Cons: Cannot be submerged long-term; no built-in temperature compensation.
• Ideal For: Daily marine aquarium sampling, marine fishery water quality checks.

🔵 Maker Advanced Models: Long-Term Monitoring (Analog)

3. Gravity: Industrial Analog EC PRO (K=1) - SEN0451 ($199.00)

• Positioning: Top-tier hydroponic/freshwater monitoring probe compatible with the Arduino ecosystem.
• Pros: Industrial-grade probe, truly enables 24/7 online monitoring; includes a PT1000 temperature sensor board for highly accurate temp readings; rich accessories (calibration solutions, waterproof joints, etc.).
• Cons: The most expensive among the 5 models; larger physical footprint (uses two conversion boards).
• Ideal For: Unattended Arduino/microcontroller projects requiring long-term monitoring, such as automated hydroponic fertilizer dispensers or ecological tank monitoring.

🔴 Professional Industrial Models: IoT & PLC Integration (RS485 / ModBus)

4. RS485 Industrial Water EC Sensor (K=1) - SEN0706 ($149.00)

• Positioning: The mainstream choice for modern agriculture and industrial IoT in freshwater environments.
• Pros: Integrated design (no scattered circuit boards); 4-in-1 data output (simultaneously outputs EC, Temperature, Salinity, and TDS); factory-calibrated; industrial wide voltage (10-30V).
• Cons: Not suitable for direct connection to a standard 5V Arduino (requires an RS485 conversion module).
• Ideal For: Smart agriculture gateway integration, water treatment plants, commercial-scale hydroponic systems.

5. RS485 Industrial-Grade Water EC Sensor (K=10) - SEN0707 ($159.00)

• Positioning: The industrial-grade weapon for harsh or high-concentration water conditions.
• Pros: Shares all the pros of SEN0706 (integrated, 4-in-1 output, IP68), while K=10 allows it to measure high-concentration liquids up to 20,000 μS/cm.
• Cons: Also requires an RS485 supported environment.
• Ideal For: Mariculture IoT monitoring, wastewater treatment plant online continuous monitoring.

Purchasing Recommendation Summary

• If you are a regular DIY player or student doing simple tap water or basic hydroponic testing, buy the DFR0300.
• If you are building an Arduino project and the probe needs to be submerged in water forever (24/7), buy the SEN0451.
• If you are an enterprise user or engineer connecting to industrial gateways or PLC equipment, choose between SEN0706 (normal water) and SEN0707 (high-salt water) based on your target water concentration. Their integration, multi-parameter output, and overall cost-performance are exceptional.