Smart Filter Monitoring & Maintenance Alerts

Your filter is the life support system of your tank. When it clogs, slows down, or stops entirely, water quality drops fast. With a power-monitoring smart plug and Home Assistant, you can track filter health in real time and get alerts before problems become emergencies.

What You'll Need

• Any aquarium filter — HOB, canister, or sponge (with air pump)
• Shelly Plus Plug S — power monitoring smart plug (preferred for wattage tracking)
• Home Assistant — already set up (see getting started guide)
• Optionally: Tuya smart plug for on/off control without power monitoring

Why Monitor Your Filter?

A healthy filter draws consistent wattage. When something changes, it means something happened:

Step 1: Plug Your Filter into a Shelly

1. Plug the Shelly Plus Plug S into a wall outlet
2. Plug your filter into the Shelly
3. Add to Home Assistant via the Shelly integration
4. Note the baseline wattage (a healthy AquaClear 50 draws ~6W)

Step 2: Home Assistant Entities

After adding the Shelly, you'll see these entities:

# Shelly filter plug entities
switch.shelly_aquarium_filter        # On/off control
sensor.shelly_aquarium_filter_power  # Current wattage (W)
sensor.shelly_aquarium_filter_energy # Cumulative energy (kWh)

Step 3: Filter Health Automations

Filter Stopped Alert

automation:
  - alias: "Filter Stopped — Emergency Alert"
    description: "Alert if filter power drops to 0W for more than 2 minutes"
    trigger:
      - platform: numeric_state
        entity_id: sensor.shelly_aquarium_filter_power
        below: 0.5
        for:
          minutes: 2
    condition:
      - condition: state
        entity_id: switch.shelly_aquarium_filter
        state: "on"
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "FILTER STOPPED"
          message: "Your aquarium filter is drawing 0W but the plug is ON. Motor failure or disconnect — check immediately!"
          data:
            priority: high
            tag: "filter-stopped"

Filter Clog Warning

automation:
  - alias: "Filter Clog Warning"
    description: "Alert if filter power spikes above normal range"
    trigger:
      - platform: numeric_state
        entity_id: sensor.shelly_aquarium_filter_power
        above: 10
        for:
          minutes: 5
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "Filter Drawing High Power"
          message: "Filter is pulling {{ states('sensor.shelly_aquarium_filter_power') }}W — may be clogged or jammed. Schedule maintenance."
          data:
            tag: "filter-clog"

Monthly Maintenance Reminder

automation:
  - alias: "Filter Maintenance Reminder"
    description: "Monthly reminder to clean filter media"
    trigger:
      - platform: time
        at: "10:00:00"
    condition:
      - condition: template
        value_template: "{{ now().day == 1 }}"
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "Filter Maintenance Due"
          message: "Time to rinse your filter media in old tank water. Don't use tap water — it kills beneficial bacteria!"
          data:
            tag: "filter-maintenance"

Step 4: Dashboard Card

Add a filter health card to your aquarium dashboard:

type: vertical-stack
title: "Filter Health"
cards:
  - type: entities
    entities:
      - entity: switch.shelly_aquarium_filter
        name: "Filter Power"
      - entity: sensor.shelly_aquarium_filter_power
        name: "Current Draw"
        icon: mdi:lightning-bolt
  - type: history-graph
    entities:
      - entity: sensor.shelly_aquarium_filter_power
        name: "Filter Wattage"
    hours_to_show: 168
    refresh_interval: 300

The 7-day power graph reveals patterns — you'll see the gradual increase as media clogs between cleanings.

Step 5: Auto-Restart After Power Outage

Smart plugs can be configured to restore their previous state after a power outage. For the Shelly:

1. In the Shelly app, go to Settings → Power On Default
2. Set to Restore Last State
3. This ensures your filter turns back on automatically after a power failure

For Tuya plugs, set the same in the Tuya/Smart Life app under Power-on Behavior.

Filter Type Tips

HOB Filters (AquaClear, etc.)

• Baseline: 4-8W depending on model
• Clean when power rises 30%+ above baseline
• Impeller rattle shows as fluctuating wattage

Canister Filters (Fluval, etc.)

• Baseline: 10-25W depending on model
• Monitor for air locks after maintenance (power drops but no flow)
• Set up a "prime reminder" automation after power outage

Sponge Filters (Air Pump Powered)

• Monitor the air pump, not the filter itself
• Air pumps draw 3-5W — a drop means the diaphragm is wearing out

My Setup

Every filter runs through a Shelly Plus Plug S. I have a Lovelace dashboard card that shows all filter wattages at a glance — if any deviate more than 20% from their baseline, the card turns yellow. One time I caught a failing impeller on my AquaClear 70 because the wattage kept creeping up over two weeks. Replaced the impeller for $8 instead of losing the whole filter.

What's Next?

• Temperature Monitoring — monitor water temp alongside filter health
• Smart Power Management — centralized power control for all devices
• Build Your Dashboard — combine all monitoring into one screen