Evaporative Cooling Fan Assembly – 120mm


This is an 120mm Evaporative Cooling Fan Assembly for rimmed or rimless aquariums.


This is an 120mm Evaporative Cooling Fan Assembly for rimmed or rimless aquariums. This cooling fan system is based on the “Evaporative Cooling” principal. This design is completely modular and is comprised of three main parts:

  1. The fan assembly in the back.
  2. A “funnel” that concentrates the air in a planar stream.
  3. The rim/rimless mount that acts as a nozzle as well.

The pieces snap in easily together with locating features on all the parts and thumb screws make the installation and opening of the system a breeze. You can easily put it together or open it up for cleanup. The whole assembly (including the fan) weighs about 600g. It is approximately 5-1/8″ wide by 7-1/4″ deep (5-1/4″ sticking out of the tank) by 5-3/4″ tall (at it’s tallest). This design is geared towards standard 120mm computer cooling fans. You can get this part in two different packages:

  • Plastic Parts Only: Only the printed parts will be provided (including the locking thumb screws). You will need to provide the fan, power supply and connecting hardware for the fan to the power supply.
  • Full Assembly: This is an out of the box ready to go solution. It will come assembled ready to mount, plug and run. A high quality moisture resistant high speed fan will be used. It will also come with a variable voltage power adapter which will give you the ability to control the speed of the fan (by controlling the voltage). The cooling fan at full speed is somewhat noisy hence a starting voltage of 7.5V is recommended.

This 120mm version of the system is more suited for bigger tanks. Depending on the size of the tank, multiple of these may be needed. You may have to experiment with how many are needed but I have tested with 30 Gallon and 50 Gallon tanks and one of these has been enough. The best place to mount these is lengthwise, i.e. one of the sides of the tank (if it’s not square) so it can sweep the whole top surface. For smaller tanks where space is a premium the 80mm version is available.

This solution can also be great to keep around for an emergency situation. For instance when you lose power for an amount of time during a hot day. The fan has very low power consumption (about 0.6W at 12V) and is ideal to operate with a battery. Installing it in a pinch like that may make a big difference on the outcome of a power failure.

General Information on Evaporative Cooling

Evaporating water takes energy which has a result of lowering the temperature of the tank water. Air is blown on top of the tank exchanging the high moisture air right over the tank with lower moisture air from the back of the fan. This promotes and accelerates further evaporation which in turn promotes further cooling. An evaporative cooling system like this can lower your tank temperature 2-3 °C (3-5 °F on average). The temperature drop you will actually get depends on a lot of factors (surrounding air relative humidity, tank surface area, air flow etc) but is expected to offer a good drop in most cases.


In general, a few things need to be considered when employing this method:

  1. Make sure you have a robust plan and procedure for your evaporation loss top off. If you have not invested in a quality ATO system, that would perhaps be worth considering before implementing this cooling method.
  2. The actual cooling effect from a system like this varies but a few degrees Fahrenheit are expected.
  3. The lower the relative humidity of the surrounding air the better.
  4. A controller system like an Apex, GHL, Hydros etc. will make controlling the system a lot easier. One conflict, depending on your setup, you may encounter without a controller is your aquarium heater kicking on “fighting” the evaporation cooling. A controller can eliminate that problem by turning the heater off while turning the cooler on and vice versa whenever needed.


Please keep in mind that these are made to order. They’re designed, printed, soldered and assembled by me. Moreover, I do not keep a big stock of fans and power adapters so these may have to be procured for your order. Please allow a few days after ordering until shipping. You can contact me if you would like a better estimate as to how long it will take to ship. Also, the fact that this is a hand assembled 3D printed product means that it might/will have some minor imperfections (that don’t hinder performance) such as surface finish imperfections, slight assembling variations etc.

Additional information

Printed Parts Material


Printed Parts Color

Black, White, Blue, Orange, Red, Clear (Translucent)

Tank Mount

Rimmed, Rimless


Plastic Parts Only, Full Assembly

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