Hydroponics success relies on several factors, and making sure that the water EC (Electrical Conductivity) range fits the plant’s needs is one of the main ones. Growers usually use an EC/PPM meter to monitor the water levels on a daily basis and before/after adding nutrients to the water. This meter needs to be calibrated from time to time using a standard EC calibration solution to stay accurate.
If you are using the full Growee automated dosing system or just the Master unit for getting real-time EC readings, it is important to make sure your EC probe is calibrated.
In this guide, I will walk you through the calibration process for the Growee EC probe and share more information about how it works, the effect of temperature on EC, and some useful tips.
Does Your Growee EC Probe Need Calibration?
Before starting, it’s important to verify whether calibration is even necessary. Here’s how you can check:
- Place the Probe in Calibration Solution: Use a 1.413 mS/cm calibration solution and let the probe stabilize for 2–3 minutes.
- Check the Reading: If the Growee App shows a reading within ±0.1 of 1.413, the probe is correctly calibrated, and you don’t need to recalibrate.
- Proper Temperature: The calibration solution must be at 25°C (77°F), as temperature fluctuations can affect EC readings.
If the reading is inside +/- 0.1 EC range at 77F the probe does not need to be calibrated. For example, if the reading is 1.3 or 1.5 inside the 1.413 calibration solution you do not need to calibrate the probe.
Before You Start the EC Calibration Process
- Get the Right Solutions: You’ll need 1.413 mS/cm and 2.77 mS/cm standard EC calibration solutions.
- Temperature of the solution: be at 25°C / 77°F. Different Temp will change the EC of the solution.
- Stop all automated programs: on the Growee App, such as smart dosing or pH control.
Step-by-Step Guide to Calibrating Your Growee EC Probe
Basic Steps:
- Wash and dry the EC probe.
- Stage 1 – Low-Value Calibration (1.413 mS/cm):
- Place the probe in the 1.413 calibration solution and let it stabilize for 2–3 minutes.
- Go to the Growee App: Modify > Manual Dosing > Probe Calibration.
- Begin the calibration 1.413 stage.
- Stage 2 – Mid-Value Calibration (2.77 mS/cm):
- Take the probe out of the 1.413, dry it, and place it in the 2.77 calibration solution.
- Let it stabilize for another 2–3 minutes.
- Begin the calibration 2.77 stage.
- Verification: After calibration, place the probe back in the 1.413 solution for 2–3 minutes to verify accuracy. The reading should be within ±0.1 of 1.413.
You can also follow this video:
Diving Deep Into the EC World
For most small-scale hydroponics growers, the two basic factors to monitor in the water or feeding solution are pH and EC (Electrical Conductivity). While pH determines how acidic or alkaline the water is, EC gives you a clear picture of the nutrient concentration. Here, I want to dive a bit deeper into EC and share some extra information that’s good to know.
What Is EC?
Electrical Conductivity, or EC, in simple words it a measure of how well a solution can conduct electricity. In hydroponics, it’s directly tied to the concentration of dissolved salts, aka minerals/fertilizers.. When you add nutrients to water, the EC increases. If the water is pure, like RO (reverse osmosis) water, the EC will be close to zero.
Think of EC as a guide to keeping your plants happy. Too low, and they’re not getting enough food. Too high, and they could suffer from nutrient burn. The goal is to keep EC within the range that’s just right for the plants you’re growing.
How Is EC Used in Hydroponics?
Growers use EC to check the source water and track and adjust the nutrient levels in their system. It’s a simple way to make sure plants are getting what they need at every stage of growth.
Check the Base Water
Before you start making a new feeding solution, it’s important to test the EC of your source water. If the EC is too high, it may mean the water contains minerals that aren’t suitable for some plants in hydroponics, or the concentration of some minerals is simply too high.
In such cases, you might need to use a filter or dilute the water with RO (reverse osmosis) water to bring the EC down to an acceptable level.
Prepare the Feeding Solution
While adding nutrients to prepare your feeding solution, follow the feeding chart provided by your nutrient manufacturer. Most charts will show both the amount of nutrients to add from each part and the target EC range for your solution.
- Adding the nutrients in small iterations instead of all at once.
- After each iteration, check the EC to make sure you’re not exceeding the recommended EC range.
Regular Testing
In recirculating hydroponic systems, it’s important to test the EC regularly. Regular checks ensure the EC stays within the ideal range and help you catch potential problems that can cause the EC to drift, such as nutrient imbalances or evaporation, which can cause the EC to drift.
Why Does Temperature Affect EC?
As the water temperature rises, the ions in the solution move faster, which makes the water more conductive. This means that even if the nutrient levels stay the same, the EC reading will go up with higher temperatures and down with lower temperatures.
For example, a solution at 25°C (77°F) might read 1.5, but the same solution at 15°C (59°F) could read closer to 1.3. This can be confusing if you’re not accounting for the temperature.
How Does Temperature Compensation Work?
Most modern EC meters, including the Growee system, have built-in automatic temperature compensation (ATC).
Here’s how it works:
- The system measures the water temperature using a sensor inside the probe.
- It automatically adjusts the EC reading to match what it would be at 25°C (77°F), which is the standard reference point for EC measurements.
This means you don’t have to worry about temperature fluctuations. The readings you see are accurate and reliable, no matter the conditions.
Wrapping It Up
It’s important to make sure your EC probe is calibrated, but over-calibration can sometimes lead to mistakes or errors. We always recommend validating the reading inside a standard 1.413 or 2.77 EC solution first before starting a new calibration. If you still think calibration is necessary, we suggest following the guide above.
