Temperature Monitoring & Smart Heater Control

Temperature swings kill fish. A stuck heater can cook your tank overnight. With an Inkbird WiFi controller and Home Assistant, you get real-time monitoring, mobile alerts, and automatic backup heater control — so you catch problems before your fish do.

What You'll Need

Inkbird ITC-306A WiFi Temperature Controller — dual probes, heating/cooling outlets
Tuya or Shelly smart plug — for backup heater control
Home Assistant — already set up (see getting started guide)
A heater (any submersible aquarium heater)

How It Works

The Inkbird controller plugs into your heater and monitors water temperature via a probe. It has its own thermostat, but by connecting it to Home Assistant via the Tuya integration, you unlock:

Temperature history graphs — see trends over hours, days, weeks
Mobile push alerts — know instantly if temperature drifts
Backup heater automation — second heater kicks on if primary fails
Dashboard monitoring — at-a-glance temp for every tank

Step 1: Set Up the Inkbird

Plug the Inkbird ITC-306A into a power outlet
Plug your heater into the Inkbird's heating outlet
Place the temperature probe in your tank (suction cup to glass, mid-water level)
Set target temperature on the Inkbird itself (e.g., 78°F / 25.5°C)
Connect to the Tuya Smart or Smart Life app on your phone

The Inkbird appears in your Tuya account and syncs to Home Assistant automatically.

Step 2: Home Assistant Entities

After Tuya integration discovers the Inkbird, you'll see:

configuration.yaml

# Inkbird entities in Home Assistant
sensor.inkbird_aquarium_temperature    # Current water temp
switch.inkbird_aquarium_heating        # Heating outlet on/off
number.inkbird_aquarium_target_temp    # Target temperature setpoint

Step 3: Temperature Alert Automations

High Temperature Alert

configuration.yaml

automation:
  - alias: "Tank Too Hot Alert"
    description: "Notify if water temp exceeds 82°F"
    trigger:
      - platform: numeric_state
        entity_id: sensor.inkbird_aquarium_temperature
        above: 82
        for:
          minutes: 5
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "Aquarium Alert"
          message: "Water temperature is {{ states('sensor.inkbird_aquarium_temperature') }}°F — above 82°F for 5 minutes!"
          data:
            priority: high
            tag: "tank-temp-high"

Low Temperature Alert (Heater Failure)

configuration.yaml

automation:
  - alias: "Tank Too Cold Alert — Possible Heater Failure"
    description: "Notify if water temp drops below 74°F"
    trigger:
      - platform: numeric_state
        entity_id: sensor.inkbird_aquarium_temperature
        below: 74
        for:
          minutes: 10
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "Aquarium Alert — Heater Check!"
          message: "Water temperature dropped to {{ states('sensor.inkbird_aquarium_temperature') }}°F — possible heater failure!"
          data:
            priority: high
            tag: "tank-temp-low"

Rapid Temperature Change Alert

configuration.yaml

automation:
  - alias: "Rapid Temperature Change Alert"
    description: "Notify if temperature changes more than 3°F in 30 minutes"
    trigger:
      - platform: template
        value_template: >
          {{ (states('sensor.inkbird_aquarium_temperature') | float -
              state_attr('sensor.inkbird_aquarium_temperature', 'last_changed_value') | float) | abs > 3 }}
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "Aquarium Alert — Rapid Temp Change"
          message: "Temperature changed rapidly — now {{ states('sensor.inkbird_aquarium_temperature') }}°F. Check the tank."

Step 4: Backup Heater Automation

Plug a second heater into a Tuya or Shelly smart plug. Home Assistant activates it only if the primary Inkbird fails.

configuration.yaml

automation:
  - alias: "Activate Backup Heater"
    description: "Turn on backup heater if temp drops below 73°F (primary heater likely failed)"
    trigger:
      - platform: numeric_state
        entity_id: sensor.inkbird_aquarium_temperature
        below: 73
        for:
          minutes: 15
    action:
      - service: switch.turn_on
        target:
          entity_id: switch.tuya_backup_heater
      - service: notify.mobile_app_your_phone
        data:
          title: "Backup Heater Activated"
          message: "Primary heater may have failed. Backup heater is ON. Water temp: {{ states('sensor.inkbird_aquarium_temperature') }}°F"

  - alias: "Deactivate Backup Heater"
    description: "Turn off backup heater once temp recovers above 76°F"
    trigger:
      - platform: numeric_state
        entity_id: sensor.inkbird_aquarium_temperature
        above: 76
        for:
          minutes: 10
    condition:
      - condition: state
        entity_id: switch.tuya_backup_heater
        state: "on"
    action:
      - service: switch.turn_off
        target:
          entity_id: switch.tuya_backup_heater
      - service: notify.mobile_app_your_phone
        data:
          title: "Backup Heater Off"
          message: "Temperature recovered to {{ states('sensor.inkbird_aquarium_temperature') }}°F. Backup heater turned off."

Step 5: Dashboard Card

Add a temperature card to your Lovelace dashboard:

configuration.yaml

type: vertical-stack
cards:
  - type: gauge
    entity: sensor.inkbird_aquarium_temperature
    name: "Water Temperature"
    unit: "°F"
    min: 65
    max: 90
    severity:
      green: 75
      yellow: 80
      red: 84
  - type: history-graph
    entities:
      - entity: sensor.inkbird_aquarium_temperature
        name: "Temperature"
    hours_to_show: 24
    refresh_interval: 60

My Setup

I run an Inkbird ITC-306A on each tank with a Shelly Plus Plug S on the backup heater. The Shelly gives me power monitoring — I can see exactly how many watts the heater draws and how often it cycles. If the Inkbird's heating outlet stops drawing power but the temperature is dropping, I know the primary heater died before the backup even kicks on.

Tips

Place the probe mid-tank, not near the heater — you want ambient water temperature
Set the Inkbird thermostat 1°F above your HA alert threshold — this gives HA time to alert you before the Inkbird takes over
Use a titanium heater for saltwater tanks — glass heaters can crack from salt creep
Check probe calibration monthly — compare against a reliable thermometer

What's Next?

Automated Feeding — auto feeders + feeding mode scripts
Smart Power Management — monitor heater energy usage
Build Your Dashboard — the complete aquarium dashboard