Emergency playbook
Reef tank power cut: what to do now
Most tanks cope with two to three hours of still water. Oxygen runs out before heat does, so get water moving first.
Do this now
- Do not feed.
- Get water moving: a battery air pump, or a powerhead on a battery or UPS. If you have nothing, scoop and pour water back in from a height every 15 minutes.
- Cold house: wrap the tank in blankets or towels and keep the lid on. Hot weather: lights off, lid open, and a battery fan across the surface.
- If you need more heat, float sealed bottles of hot (not boiling) water, checking the temperature every half hour.
- Only run a generator outdoors.
Why each step
- 1. Do not feed.
- Food left uneaten rots and uses oxygen that the still water cannot replace (Reef Builders).
- 2. Get water moving: a battery air pump, or a powerhead on a battery or UPS. If you have nothing, scoop and pour water back in from a height every 15 minutes.
- Livestock usually show no stress for two to three hours of still water; after that, oxygen is the first limit. BRS says a tank with flow should survive two to three days without heaters, filtration or lights.
- 3. Cold house: wrap the tank in blankets or towels and keep the lid on. Hot weather: lights off, lid open, and a battery fan across the surface.
- A fan across the water surface cools by about 2 to 3 C. Overheating is worse than cooling because warm water holds less oxygen (Reef Builders).
- 4. If you need more heat, float sealed bottles of hot (not boiling) water, checking the temperature every half hour.
- This is our reading: no source gives a heating rate, so change it gently and check often.
- 5. Only run a generator outdoors.
- Generators make carbon monoxide. Controllers and LED lights also need a pure sine wave output (Reef Builders).
Once the tank is stable, what next?
- Before the power returns, unplug the return pump and skimmer at the wall. Check the sump can hold the water that drained back when the pump stopped, so it will not overflow on restart.
- Start the return pump, then the powerheads. Watch the sump level for a few minutes.
- Start the heaters once flow is running.
- Leave the skimmer off for 30 to 60 minutes so it does not overflow while the water settles.
- Lights last.
- If the cut lasted more than about 12 hours, test ammonia and remove anything dead.
How do I stop it happening again?
- Keep a battery air pump with fresh batteries, or a powerhead on a UPS. BRS lists battery backup as the key item.
- Test the backup every six months, and know how long it runs.
- Label every plug so a family member can restart things in order.
- A controller that sends power-loss alerts to your phone (BRS).
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