# How do I calibrate the CO2 sensor?

### Why is CO₂ calibration important?

Over time, CO₂ sensors naturally drift, leading to inaccurate readings. To ensure precise data and optimal plant growth, we recommend calibrating your Grow Sensor’s CO₂ sensor every six months.

#### What happens if you don’t calibrate?

* Overestimated or underestimated CO₂ levels can lead to inefficient CO₂ supplementation, wasting resources or stunting plant growth.
* Incorrect readings may cause poor climate control adjustments, reducing yield and plant health.

Regular calibration ensures accurate CO₂ monitoring, allowing for better environmental control and improved plant performance.

### How to calibrate your grow sensor’s CO₂ sensor

Before you start:

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**Choose the right calibration environment**

Calibrate outdoors in fresh air, away from traffic, buildings, or direct sunlight. Outdoor air typically contains \~420 ppm CO₂, providing a reliable baseline.
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**Check battery levels** 

Ensure your Grow Sensor has enough battery to complete the process.
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**Avoid enclosed spaces**

Do not calibrate indoors, in a greenhouse, or near plants, as CO₂ levels may be artificially elevated.
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### Step-by-step CO₂ calibration process

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**Move the Grow Sensor outdoors** 

Find an open-air location, away from buildings and direct sunlight.
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**Press and release the button when the LED turns purple**

This enters CO₂ calibration mode.
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**Wait for the purple LED to flash for up to 60 seconds**

The sensor is preparing to calibrate.
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**Press and release the button again within 60 seconds**

The purple LED will flash faster, indicating
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**Calibration begins:**

* Fast-flashing green LED (30 seconds) – The sensor is actively calibrating.
* Fast-flashing red LED (30 seconds) – The calibration process is completing.
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**Calibration complete** 

The LED will flash white once, confirming successful calibration.
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**Return the Grow Sensor to your grow environment**

Press the button to wake it up.
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For a full breakdown of button functions, check out the [complete flow diagrams here](https://www.figma.com/board/WWU8B2Y140AZug7zJ6ojpW/Grow-Sensor-customer-button-flow?node-id=0-1\&t=1AYRtf3VV67pDGgF-1).

### **Troubleshooting CO₂ calibration issues**

#### **What if the calibration fails?**

If calibration fails, the red LED will continue flashing instead of flashing white at the end.

#### Possible causes & solutions:

* **Calibrated in an enclosed or CO₂-rich environment** → Move the sensor to an open outdoor space and try again.
* **Calibration was interrupted** → Restart the process from step 1.
* **Battery too low** → Charge the sensor and attempt calibration again.

#### **How do I cancel a calibration?**

To abort the calibration process, press and hold the button for 5 seconds. The sensor will return to normal operation.

#### **What happens if I forget the sensor outside?**

Your Grow Sensor will automatically wake up and resume normal readings. However, prolonged outdoor exposure isn’t recommended, so be sure to bring it back inside once calibration is complete.

Still have questions? Contact us at <support@growsensor.co> we’re happy to help!

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