Temperature Plunge

What’s Happening

Most heater failures are silent. The water cools slowly overnight and you notice it at your morning check. A rapid drop stresses fish; a slow drop over days can kill cold-sensitive species.

Steps to Fix It

1. Check the heater first. Is it plugged in? Is the indicator light on? Unplug and re-plug. A heater that’s on but not heating may have failed internally.
2. Do not add hot or boiling water directly to the tank. Thermal shock from a sudden temperature spike is fatal.
3. Float sealed bottles or bags of warm water (not boiling — aim for 30–35°C water in the bag) to raise tank temperature gradually. Aim for no more than 1–2°C per hour.
4. Log temperature every few hours until stable. Once a replacement heater is installed, monitor for 24 hours.

Prevention

• Run two smaller heaters instead of one large one — redundancy prevents a single point of failure.
• Check your heater light weekly as part of maintenance.

Track your temperature and get step-by-step crisis alerts in the AquaKeepers app.