Add documentation for hanna integration

source/_integrations/hanna.markdown

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+---
+title: Hanna
+description: Instructions on how to integrate HannaCloud within Home Assistant.
+ha_release: 2025.12
+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.
+
+## Supported devices
+
+The following devices are known to be supported by the integration:
+-  Hanna Instruments BL122
+-  Hanna Instruments BL132
+
+## Prerequisites
+
+Before you can add the Hanna integration, you need:
+
+- A [HannaCloud](https://www.hannacloud.com) account.
+- Your HannaCloud login credentials (email and password).
+- A Hanna Pool Controller device that is connected to your HannaCloud account.
+
+{% include integrations/config_flow.md %}
+
+### Configuration parameters
+
+{% configuration_basic %}
+email:
+  description: The email address of your HannaCloud account.
+password:
+  description: The password associated with your HannaCloud account
+{% endconfiguration_basic %}
+
+## Data updates
+
+The integration will update its sensors by {% term polling %} the HannaCloud account for new values. 
+
+
+## Supported functionality
+
+### Entities
+
+The Hanna integration provides the following entities.
+
+#### Sensors
+- **Chlorine flow rate**: Monitors chlorine dosing rate
+- **Chlorine ORP value**: Measures oxidation-reduction potential with calibration data as attributes
+- **pH Acid/base flow rate**: Monitors acid/base chemical dosing rate
+- **pH value**: Measures pH level with calibration data as attributes
+- **Air temperature**: Air temperature reported by the device
+- **Water temperature**: Water temperature reported by the device
+
+
+## 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 %}