Given that I live in a very hot place where the temperatures get extremely hot (especially during the summer) and I have a 55 gallon (around 210 liters) tank with a few angelfish, an aquarium chiller is highly necessary. I want to prepare beforehand and I've been on the lookout for a great chiller for a while now, did my research and all. I've been looking at this article about chillers and I think it's all very well explained and sounds promising, but I'm still not sure whether to get one of these.

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    Welcome to Pets Stack Exchange! :) It's worth noting that whilst some of the users here coincidentally could be 'professionals', the majority of us are enthusiastic hobbyists or amateurs. Is your question 'how to select a good chiller?' or perhaps 'what to look for in a chilling system?' If you could edit your question to clarify that would help us answer.
    – Henders
    May 14 '18 at 15:22

Firstly, you'll probably want to ensure that there is no other way for you to cool your tank before you buy a chiller because an aquarium chiller unit represents a reasonable investment. Indeed, the cheapest reputable chiller I've found was about £100 but they can range vastly some of which are over £600.

Have you tried the alternatives?

So before you grab yourself a chiller, you'll probably want to try some of the cheaper methods before you fully invest. Okay, so what are these alternatives?

Keep the room cool

Many aquarium hobbyists will choose to heat or cool the room their tanks are in if they have multiple tanks that require the same temperature. This means you don't have to buy individual heaters/coolers for each tank. You can simply heat the room to the desired temperature. In this specific case, this will require you to get a unit to cool the room but if you are too hot as well, then that may be something to consider instead.

Create more surface agitation

An agitated surface helps to increase the surface area of your aquarium which helps evaporation (see below). Adding an air stone or adjusting your filter to create a more disturbed surface will aid this.

Use evaporation!

If you can get a fan that will move air across the top of the aquarium, the evaporation can help to cool the water down. Obviously, if you're using evaporation then you'll end up with more topping off because you'll lose water from your aquarium at an exaggerated rate. This is not always possible certainly for tanks that need enclosed lids. You can also get specially designed aquarium hoods to extract hot air from inside but there is a cost associated with these.

Float frozen water bottles

Okay, this one isn't bullet proof. You'll obviously need the frozen water first and you'll need access a bunch of them. It is worth mentioning though simply for emergencies.

Alright, none of those work for you? Let's talk chilling units.

The first thing you'll want to do is think about how each chiller will perform and how easy it will be to live with. For me, we can split this into a few categories.

Ability to chill

Most chillers will have a volume that they claim to chill successfully. There will also be limits on the temperatures that they will effectively chill at. For example, if your water is 40 degrees, the unit will be less effective than if your water is 30 degrees. Some will also have a watt rating which should also give you some indication as to how good they are.

Heat produced

A lot of chillers will produce heat in the room they are working. Mainly the heat they produced can only be worked out by other people's reviews but perhaps power consumption will give you a point in the right direction. If your chiller is going to heat the room more, you may find limited ability to chill your water.

Power Consumption

This might not be a problem for you but some of the chillers I've seen out on the internet will use a lot of energy to power. If you've got to run this continuously, this may be a factor worth considering.

Size and Operating Volume

If this tank is going to be in a room that will need to be quiet (such as a bedroom) you may wish to find figures on how noisy the units are. You may struggle to find these metrics from the sellers but reviews should highlight any potential issues. Some of the units I've looked at are pretty bulky, so if you're looking for a tidy finish to your tank, make sure it fits in a cupboard somewhere!

Cost / Quality

Finally, you'll obviously need a reasonable budget to be able to buy and run one of these units. There are a lot of cheaper non-brand products out there but I would steer clear of these. Often they can exhibit poor workmanship and for a product which will heavily utilise power and water(!), you don't want to discover they skimped on the safety aspects.

Cheaper DIY Version?

If money is a limiting factor and you're interested in a DIY solution, then there's a fantastic video which will help to explain the process to you. Check out this video to see how to build your own aquarium chiller using an old fridge, pump and some hosepipe.


I can actually help with this.

I too have a 55 gallon (around 210 liters) fish tank. (actually a 54 gallon corner).

First thing is: How hot is too hot? Is 78-80 °F (26-27 °C) too hot and never should be seen? This means you need a chiller.

Is 78-80 °F ok, you should consider a small fan that can be pointed at the surface of the water.

I've used both.

This is the chiller that runs perfectly on a 55 gallon tank (unless you are cooling a nuclear reactor ie: a faulty AC pump): 1/10th HP and I also ran/run a small fan.

Here is the verdict: unless its absolutely necessary to keep the temps very low, go with the fan first. They cost about $10 and will show you pretty quick if they are adequate.

Note on the chiller: when it runs it pulls out the heat from the water then adds its own heat (the compressor running) and expels it all into the room its in. So your room will get stupid hot without proper A/C.

Never keep the chiller inside the cabinet it needs proper ventilation, otherwise its useless.

Hope this helps!


In the Amazon area, where angels are native, the water temperature is often 86 °F (30 °C). This is from a quick look at H. Bleher's Discus book. He has collected fish throughout central and south America and lists water parameters (temperature, oxygen, conductivity - salt, etc.) from hundreds of locations. Water movement/aeration is more important at higher temperatures. So unless your tank is very crowded and over 86 °F, I wouldn't worry.

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