Build Your Own Aquarium Chiller – Step By Step Guide

Last Updated on December 7, 2021 by Marco C.

Want to build your own aquarium chiller but not sure how to do it? This is the simplest guide to making it.

Depending on where you live, an aquarium chiller can be an important and sometimes life-saving piece of your aquarium equipment. Unfortunately, its prices vary up to several hundred dollars, which is not convenient for everyone’s pocket. However, let’s not forget that there are creatives among us who adore challenges and various DIY projects.

We are therefore here to meet everyone’s needs and help ensure a healthy aquatic environment. Are you ready for something new? Continue reading our guide to how to build your own aquarium chiller.

What Is An Aquarium Chiller

The easiest/uncomplicated way to look at an aquarium chiller is as a kind of refrigerator. Or if you want – like a fish tank fan that works reverse of a heater. Which would actually mean it lowers the temperature when it gets too high to a sufficient and suitable range for your fish.

It is important to remember that they are not necessary (sometimes they are very expensive), but they can be useful in some situations. This is most often the case for aquariums located in places with “bipolar weather,” that is, where summers are sizzling hot, and the winters are freezing cold.

It is, therefore, a small refrigerator installed in line with an external aquarium filter to cool the water as it passes through the system. The modern ones can be very advanced. For example, they may have optics over large amounts of water and be able to sense temperature changes without any of your input. However, keep in mind that it will potentially cost hundreds of dollars.

On the other hand, there are much simpler and cheaper solutions that require only a little of your creativity and time. And no, you don’t have to be an expert! Building your own DIY aquarium chillers is not complicated at all.

We will show you how to build it on a method based on sending water through a mini-refrigerator to cool it and then return it to the aquarium. Well, let’s go!

Read more about: Looking For The Perfect Saltwater Aquarium Starter Kit?

Material Needed

To make your homemade aquarium chiller you will need the following components:

  • a mini-refrigerator,
  • pipings,
  • a spade drill,
  • silicone or expanding foam.

Choosing Your Refrigerator

A mini-fridge is actually the best option to choose from. It is easy to move and even easier to store. Also keep in mind, the bigger the refrigerator, the cooler your aquarium water will be as it stays in the system longer.

Price is also another aspect that plays a big role. Buying a refrigerator will be the most expensive part of making your DIY aquarium chillers. Feel free to go online and search for used devices. You don’t need to strive for anything luxurious, but try to find a device that also has a freezer – it will help to circulate cold air.

Choosing Your Piping

Pipe selection is also one of the important aspects. You will need a lot of them – trust us, the price will play an important role. Choose the cheaper option, for example, a garden hose is a good choice for the internal piping. In addition to being cheap, it is also sturdy, and well insulated.

How many pipes you will need depends on the size of the refrigerator. The math is simple, the more piping = the greater the effect of the cooler. Also, make sure the pipes you choose are opaque. This will control algae and their unwanted reproduction which ultimately reduces water quality and restricts flow.

How To Make A Homemade Aquarium Chiller

There are several methods to build your own aquarium chiller, but this time we decided to show you how to do it more cheaply. Most important of all, you don’t need any technical DIY skills. Well, let’s start making it!

Clearing The Refrigerator

This is a step you certainly don’t want to skip. Disconnect and separate everything inside the refrigerator to make enough free space. Remove all shelves, gratings, and bottle holders from the inside, but don’t remove the small freezer section and thermostat. Instead, detach the door to it, leaving the freezer tray. This will allow cold air to circulate through the system.

Adding Internal Piping

The first thing is to remember to wash the pipes to remove dust or particles inside them. As we have already stated, you will need lots of internal piping to fill your refrigerator.

The next step is to connect all the pipes you will use inside the refrigerator. Connect them to each other until you get one long pipe, and then cut off any connectors that might be at each end. When placing inside make sure there are no kinks that will restrict water flow (use coiling).

Drilling Holes

Water from the aquarium needs a way to get in and out of the refrigerator, so you will need to drill two holes to run those pipes through. It doesn’t matter where you drill them, it’s just important that they don’t go through the parts responsible for maintaining the refrigerator. It would be best to choose a place that will allow for a minimum length of pipe from your aquarium to the refrigerator. Use a spade drill bit that is slightly smaller than the diameter of the pipe, this will allow a firm grip.

Installing The Piping

Insert the piping through the two holes you made. You will do this by sliding one end of the internal piping through one hole and the other end through the second hole. The cooling process will look like this: water will enter through one end, travel through the chiller tubing, and exit through the other end.

Don’t forget to silicone or better yet, insulate the entry and exit holes using expanding foam around the piping. This will provide extra strength and will keep them in place.

Preparing The Chiller

And that’s basically it, your homemade aquarium chiller is done! Remember to set the thermostat to the lowest temperature and leave the refrigerator on for at least 24 hours. After that, you can attach it to your aquarium without any worries.

Connecting To Your Aquarium

There is no concrete and unique way to connect the chiller to your aquarium. Choose the way that best suits your needs.

Some of the most common ways are:

  • Connect the two devices by adding another pump to your aquarium, separate from the filter.
  • Adding a valve at the connection between the piping from the aquarium and the chiller piping, for easier control of the flow and thus the temperature.
  • Connect the chiller to a canister filter to keep the water moving through the chiller as part of the route of movement.


Now that you’ve put all the pieces together, keep an eye on it for a while. Keep track of all changes and possible leaks. Whether everything is in order will soon be obvious.

Everything works? Well, that’s great – you’re done!

We hope you found this step-by-step guide on how to build your own aquarium chiller useful. If you have any questions or ideas, write to us in the comments below!

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