My axolotl tank is getting too warm during the recent heatwaves, but I cannot afford a commercial aquarium chiller right now. Are there safe, inexpensive ways to build or repurpose a cooling system? I have some old PC components, pumps, tubing, and other spare materials available. I have tried using frozen bottles, but they take too long to refreeze and do not provide consistent cooling.
5 Answers
A safer temporary method is to circulate the aquarium water through metal tubing placed in an ice-water bath inside a cooler. A small pump can move the water through the coil and return it to the tank. Keep the cooling loop separate from the ice and melting water, monitor the temperature closely, and avoid dropping the temperature too quickly.
Evaporative cooling may be the simplest DIY option. You could use a small water pump to move water through a cooling tower or over a surface while a fan blows across it. As the water evaporates, it cools, but you will need to top off the tank regularly. This works best in a dry climate and can increase humidity in the room.
A small refrigerator can potentially be used as an external cooling loop: circulate aquarium water through tubing inside the refrigerator and return it to the tank with a suitable pump and thermostat. However, this needs careful leak prevention, food-safe tubing, electrical protection, and constant temperature monitoring. Never place the aquarium itself in a refrigerator, and avoid homemade systems that could expose the animal to sudden temperature changes.
You can place the aquarium in a larger tub and surround it with cool water. When that bath warms up, replace the bath water with cooler water. It is labor-intensive and uses more water, but it can help stabilize the temperature during short heatwaves. For a long-term solution, a proper aquarium chiller is more reliable.
That could work as an emergency measure, but I am hoping to build something more consistent from the spare parts I already have.
Old PC fans can help with surface evaporation, especially if you remove or open the lid enough to let air move across the water. A Peltier cooling module is another possible experiment, but it needs a proper heat sink and fan on the hot side, plus reliable temperature control. Without those, it can overheat or cool the water unevenly.
Small evaporative coolers can sometimes be found for around $45, though their effectiveness depends heavily on the humidity where you live.