Add documentation for new integration Hanna

source/_integrations/hanna.markdown

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+---
+title: Hanna
+description: Instructions on how to integrate HannaCloud within Home Assistant.
+ha_release: 2025.7
+ha_category:
+  - Sensor
+ha_codeowners:
+  - '@bestycame'
+ha_quality_scale: bronze
+ha_domain: hanna
+ha_integration_type: device
+ha_iot_class: Cloud Polling
+ha_config_flow: true
+ha_zeroconf: false
+ha_platforms:
+  - sensor
+---
+
+The **Hanna** {% term integration %} fetches data from your [Hanna Pool Controller](https://www.hannainstruments.be/en/Applicatons-measure-analyze/swimming-pool/ph-chlorine-control/systems/) device, by connecting to your [HannaCloud](https://www.hannacloud.com) account.
+
+HannaCloud is 
+
+{% include integrations/config_flow.md %}
+
+### Configuration parameters
+
+{% configuration_basic %}
+email:
+  description: The email address of your [HannaCloud](https://www.hannacloud.com) account.
+password:
+  description: The password assiciated with your [HannaCloud](https://www.hannacloud.com) account
+{% endconfiguration_basic %}
+
+## Data updates
+
+The integration will update its sensors by polling the [HannaCloud](https://www.hannacloud.com) account every 5 seconds for new values. 
+
+
+## Available sensors
+
+The following sensors are supported:
+
+- Air Temperature: Air Temperature reported by the device
+- Alarms: Binary sensor with alarm and warning details as attributes
+- Chlorine Flow Rate: Monitors chlorine dosing rate
+- Chlorine ORP value: Measures oxidation-reduction potential with calibration data as attributes
+- Chlorine Pump Status: Indicates if the pump is running or not
+- pH Acid/Base Flow Rate: Monitors acid/base (pH-) chemical dosing rate
+- pH Pump Status: Indicates if the pump is running or not
+- pH value: Measures pH level with calibration data as attributes
+- Service Status: Reports the condition of the device's service light
+- System Status: Reports the overall system status
+- Water Temperature: Water temperature reported by the device
+
+All sensors include a `last_updated` attribute with the timestamp of the last data update.
+
+## Troubleshooting
+
+There are no commonly known issues with this integration.
+
+## Removing the integration
+
+This integration follows standard integration removal. No extra steps are required.
+
+{% include integrations/remove_device_service.md %}