# Calibration Guide

Precise readings are the difference between a thriving garden and a failed crop. HydroponicOne provides built-in tools to calibrate your sensors via the dashboard.

![Calibration Page](../assets/images/Screenshot-HydroponicOne-calibration.png)

```mermaid
graph LR
    subgraph "User Interface"
        UI["React Dashboard"]
        Live["Live Data Window"]
    end

    subgraph "Asynchronous Messaging (MQTT)"
        Broker["MQTT Broker"]
    end

    subgraph "Edge Node (ESP32)"
        Device["Firmware Controller"]
        LFS[("LittleFS (config.json)")]
        Sensors["Raw Voltages / ADC"]
    end

    %% Flow
    Sensors -- "Raw Data" --> Device
    Device -- "telemetry:status" --> Broker
    Broker -- "Update UI" --> Live

    UI -- "cmd:calibrate {midpoint}" --> Broker
    Broker -- "Command" --> Device
    Device -- "Map & Save" --> LFS
    LFS -- "Applied Offset" --> Device
    Device -- "Pub Confirmation" --> Broker
    Broker -- "Success Notification" --> UI
```


## 🧪 pH Calibration (Two-Point)

1.  Prepare pH 4.0 and pH 7.0 buffer solutions.
2.  Submerge the probe in **pH 7.0** solution.
3.  Wait for the reading to stabilize on the Dashboard.
4.  Click **Calibrate PH7** in the UI.
5.  Rinse the probe and repeat for **pH 4.0**.

![pH Calibration](../assets/images/Screenshot-HydroponicOne-ph-calibration.png)

## ⚡ EC (Conductivity) Calibration

1.  Dry the EC probe completely.
2.  Click **Calibrate Dry** (sets the base voltage).
3.  Submerge in a known solution (e.g., 1.41 mS/cm).
4.  Enter the solution value in the Dashboard and click **Calibrate Scale**.

![EC Calibration](../assets/images/Screenshot-HydroponicOne-ec-calibration.png)

## 📏 Reservoir (Tank) Calibration

This sets the "Empty Distance" for your ultrasonic sensor.

1.  Ensure your reservoir is completely empty.
2.  The ultrasonic sensor should have a clear path to the bottom.
3.  Click **Calibrate Empty** on the Dashboard.
4.  The system will now measure water height as `EmptyDistance - CurrentReading`.

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### Troubleshooting
Having issues with readings? See [**Step 6: Troubleshooting**](./06_TROUBLESHOOTING.md).