Best Aquarium Thermometer – Top 10 Reviews, Guide, FAQs Upd.

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You’ll agree with us when we say that finding an accurate aquarium thermometer with a quick response rate is actually a lot harder than it sounds. 

That’s why we decided to put all the popular aquarium thermometers to the test to bring you this comprehensive list. 

In today’s post, we’ll discuss the things you should look for when purchasing an aquarium thermometer and why an aquarium thermometer can be a valuable tool for a fishkeeper.

Top Pick

This thermometer sticks to the outside of your aquarium. Since it’s on the outside, you don’t have to worry about it being harmful to your fish and it’s also extremely accurate.

Runner Up

This product also attaches to the outside of your aquarium and it changes colors depending on the temperature. This makes it easy to read and appealing to look at.

Also Great

Coming with a colored digital display, this product makes it very easy to read the temperature off of it. It has a quick response rate and has multiple mounting options.

After testing tons of thermometers under several different conditions, we’ve determined these three to be the best of the bunch. 

Now, let’s get into the reviews for the top 10 best aquarium thermometers.

Best Aquarium Thermometers - Best 10 Reviews

1. All-Around Best Aquarium Thermometer - American Thermal Horizontal Aquarium Thermometer Review

The American Thermal Horizontal Aquarium Thermometer features a very easy way to mount onto your aquarium. It utilizes liquid crystals as an adhesive to stick to your aquarium wall. Now, bear in mind it sticks to the outside wall of your aquarium so you don’t have to worry about any sort of reaction or harmful chemicals seeping into your tank water. 

The thermometer started displaying an accurate reading of the tank water within a minute of us sticking it onto our aquarium. You’ll find that the numbers are also big and very easy to read.

Features of American Thermal Horizontal Aquarium Thermometer – Best Aquarium Thermometer

  1. Dimensions: 7.4 inches by 1 inch by 0.1 inches
  2. Weight: 0.32 ounces
  3. Temperature range: 66 to 84 degrees Fahrenheit (18 to 29 degrees Celsius) 
  4. Movable
  5. Works for any size of aquariums
  • Accurate
  • Easy to read
  • Easy to set up
  • Doesn’t react with water or aquarium walls
  • Can be easily relocated
  • Might respond slowly in acrylic tanks

If you want a thermometer that’s not too much of a hassle to set up and won’t disturb your fish, this is the product you’re looking for. It’s accurate and fast.

2. Best Color-Changing Aquarium Thermometer - SUKRAGRAHA Traditional Stick-on Digital Temperature Thermometer Review

This thermometer also features a stick-on approach. It sticks easily to the outside surface of your aquarium to accurately tell you the temperature of the tank water inside. 

It features a colored display that tells you the current temperature as well as the temperature that the tank water is slowly approaching/going towards. 

It responds to temperature change very quickly and is accurate to 1 degree. 

The fact that you get 10 of them in one set means that if you have a large aquarium, you can definitely use more than one on it to measure different areas of your aquarium and make sure they’re all homogenous.

Features of SUKRAGRAHA Traditional Stick-on Digital Temperature Thermometer

  1. Dimensions: 5.12 inches by 0.71 inches by 0.1 inches
  2. Weight: 0.3 ounces
  3. 10 thermometers in one set
  4. Temperature range between 18-34 degrees Celsius (64-93 degrees Fahrenheit)
  5. Color changing property for dynamic temperature reading
  • Great value for money
  • Easy to use
  • Easy to read
  • Quick response rate
  • Displays in both Celsius and Fahrenheit
  • Some may consider the temperature range to be small

If you’re looking for an easy-to-use thermometer with a great bang for your buck, this product is perfect for you. It features a clear, simple display with colors.

3. Best Digital Aquarium Thermometer - Keynice Digital Thermometer Review

This is a nifty little aquarium thermometer that can be used effectively to monitor aquarium temperature at a glance. 

It features a switch to convert the reading between Fahrenheit and Celsius and the reading itself is accurate to 0.1 degrees.

You only need to dip the probe into the tank water in order to get an accurate reading. The thermometer LCD display can be mounted outside of the water so you can clearly see what it says. 

The build quality of the thermometer is impressive and it does not feel flimsy at all.  

Features of Keynice Digital Thermometer

  1. Dimensions: 4.2 inches by 1.6 inches by 1.6 inches
  2. Weight: 3.2 ounces
  3. Temperature range: -58 to 230 degrees Fahrenheit (-50 to 110 degrees Celsius)
  4. Digital LCD Display
  5. Rust-proof sensor probe
  • Quick response rate
  • Very large temperature range
  • Easy to read
  • Easy to set up
  • Inexpensive
  • Needs a power source

If you’re looking for a thermometer with a digital LCD display with a very sensitive probe and fast response rate, this product is ideal for you. It’s built to last and has a very clear display.

4. Best Floating Aquarium Thermometer - Marina Floating Thermometer Review

The Marina Floating Thermometer is a beautifully designed apparatus which you can easily mount within your aquarium with the help of its suction cup. The suction cup holds the thermometer very well even if you submerge the thermometer entirely in water. 

It features a green zone on its display which ranges from 78 to 80 degrees Fahrenheit (25 to 27 degrees Celsius) which is the typical temperature range in which most tropical fish should be accommodated at. 

It features big numbers that are very easy to read even from a distance. 

Features of Marina Floating Thermometer

  1. Dimensions: 7.0 inches by 4.0 inches by 1.0 inch
  2. Weight: 0.8 ounces
  3. Temperature range: 32 to 120 degrees Fahrenheit (0 to 50 degrees Celsius)
  4. Suction Cup for mounting
  5. Safety zone indicator
  • Accurate
  • Quick response rate
  • Big, bold numbers for easy reading
  • Provides temperature in both Celsius and Fahrenheit
  • Suction cups have a strong hold even completely underwater 
  • Suction cup gives off a slight odor

If you’re looking for a beautiful thermometer that you can submerge within your aquarium, this product is ideal for you. It has a large temperature range with a safety indicator and a great response rate.

5. Best Magnetic Aquarium Thermometer - JW Pet Company Smarttemp Thermometer Review

The JW Pet Company Smarttemp Thermometer is made from plastic which may seem like a bad thing in some aspects but in terms of reading the temperature, this actually works in its favor. A lot of glass thermometers are hard to read from a distance whereas this plastic thermometer can easily be read at a glance from a distance even if it’s completely submerged in water. 

It mounts to the inside of your aquarium using a magnet on the outside surface of the wall. This is ingenious and is great if you want to avoid thermometers with suction cups which can cause chemicals or odors to seep into your aquarium.

Features of JW Pet Company Smarttemp Thermometer

  1. Dimensions: 4.0 inches by 7.0 inches by 0.5 inches
  2. Weight: 1.12 ounces
  3. Temperature range: 30 to 100 degrees Fahrenheit (0 to 40 degrees Celsius)
  4. Optimal temperature indicator
  5. Magnetic mounting mechanism
  • Easy to mount with magnet
  • Easy to read 
  • Fun, old-school aesthetic
  • No need of suction cups that may react with tank water
  • Affordable
  • Seems fragile

If you’re looking to avoid suction cup thermometers and want a thermometer with a big and clear display, this is the product for you. You’ll find it very easy to set up and it’s highly accurate.

6. Best Affordable LCD Aquarium Thermometer - TOOGOO Digital LCD Thermometer Review

People often want digital LCD thermometers for their aquariums but the prices of such thermometers can get ridiculously high. This is where the TOOGOO Digital LCD Thermometer comes in. It gives you the accuracy, quickness and aesthetic of an LCD thermometer at less than half the price of typical LCD thermometers. At less than $4, this product is pretty much a steal. 

It’s powered using a button battery which you get included within the package and this battery lasts for an astonishingly long time. 

It’s fairly small in size and doesn’t have a large footprint on your tank which is great since it won’t attract any attention towards itself.

Features of TOOGOO Digital LCD Thermometer

  1. Dimensions: 3.0 inches by 5.0 inches by 1.0 inch
  2. Weight: 3.52 ounces
  3. Temperature range: 14 to 122 degrees Fahrenheit (-10 to 50 degrees Celsius)
  4. LCD size: 1.0 inch by 0.5 inches
  5. Waterproof, highly sensitive probe
  • Very quick response rate
  • Accurate to 0.1 degrees
  • Easy to set up
  • Sturdy
  • Lightweight
  • Display is not backlit and may be difficult to read

If you’re looking for an LCD thermometer at a reasonable price, this is the product for you. Not only is it lightweight and compact, it’s also accurate and fast.

7. Best Aquarium Thermometer for Water Changes - Cooper-Atkins Waterproof Reduced-Tip Digital Thermometer Review

Many newcomers and even veterans find it difficult to maintain the temperature of their aquarium’s water when they are performing water changes. This is something where this thermometer can come in very handy. It can easily be mounted and dismounted and it gives an instant reading. So, you can easily measure the water in your bucket and the water in your tank and make adjustments accordingly until they’re the same temperature. 

The thermometer has a digital display that’s very easy to read, it’s powered using batteries which are provided with it and you’ll find that it’s highly accurate even when you constantly change the settings of your aquarium heater.

Features of Cooper-Atkins Waterproof Reduced-Tip Digital Thermometer

  1. Dimensions: 5.0 inches by 9.0 inches by 5.0 inches
  2. Weight: 0.16 ounces
  3. Temperature range: -40 to 450 degrees Fahrenheit (-40 to 232 degrees Celsius)
  4. Batteries included
  5. Instant reading for aquarium water changes
  • Highly accurate
  • Instant reading in response to temperature changes
  • High-quality build
  • Easy-to-read display
  • Stylish design
  • Expensive

If you’re having trouble maintaining water temperature while performing water changes, this product is definitely for you. It gives an instant reading and is a great help while trying to keep the temperature consistent.

8. Best Saltwater Aquarium Thermometer - Lifegard Aquatics Digital Temp Alert Review

Many fishkeepers care dearly for their pets and are often checking the aquarium to see whether all the parameters are in order or not. This thermometer is made for them as it provides an alert system for whenever the temperature goes below or above the optimal level. 

You can set this temperature yourself and every time it goes into the danger zone, lights will flash and a sound will be played to alert you so you can come and make the necessary changes. 

It’s made from materials that are non-reactive with saltwater so you can use it in both freshwater as well as saltwater fish tanks.

Features of Lifegard Aquatics Digital Temp Alert

  1. Dimensions: 6.0 inches by 1.2 inches by 8.2 inches
  2. Weight: 6.4 ounces
  3. Temperature range: 32 to 212 degrees Fahrenheit (0 to 100 degrees Celsius)
  4. Alarm for low or high temperature
  5. Suction cup mounting
  • Easy to mount
  • Easy to read
  • Long-lasting
  • Sound and flashing notification for dangerous temperatures
  • Display can switch between Celsius and Fahrenheit
  • Slightly heavy for an aquarium thermometer

If you’re looking for a thermometer with an alert system for whenever the temperature isn’t right, this product is definitely for you. It features a simple, functional design and will last you a lifetime.

9. Best Small Aquarium Thermometer - Fluval Nano Thermometer Review

Many fishkeepers don’t enjoy having a lot of equipment within their aquarium. A lot of the times, they try to hide filters and heaters with decorations, ornaments and plants. The last thing they want is an ugly thermometer taking up space and taking away attention from their beautiful fish. 

The Fluval Nano Thermometer was made for such fishkeepers. It features a small, compact and inconspicuous design. You will barely notice its presence within your aquarium and yet, despite its small size, its reading is still very easy to read due to its bold, big numbers. 

Features of Fluval Nano Thermometer

  1. Dimensions: 1.0 inch by 2.3 inches by 4.0 inches
  2. Weight: 0.48 ounces
  3. Temperature range: 35 to 125 degrees Fahrenheit (2 to 52 degrees Celsius)
  4. Suction cups for mounting
  5. Unobtrusive design
  • Very lightweight
  • Extremely compact
  • Easy to read
  • Easy to install
  • Highly accurate
  • Seems slightly flimsy

If you’re looking for a thermometer that doesn’t call attention to itself, this product is great for you. It’s extremely lightweight, easy to handle and works very well in all types of aquariums.

10. Best Aquarium Thermometer with Long Cord - KollerCraft TOM Temp Alert Digital Thermometer Review

The KollerCraft TOM Digital Thermometer is a wonderful little piece of equipment as it features a very sensitive probe that accurately describes water temperatures and immediately shows any changes that occur within it. 

You’ll find the cord of the probe to be quite long which is a welcome feature if you want to move it around within your aquarium to make sure the temperature is nice and homogenous throughout it. 

The suction cup it comes with is also very strong and is able to hold the thermometer to your aquarium wall quite firmly.

Features of KollerCraft TOM Temp Alert Digital Thermometer

  1. Dimensions: 7.5 inches by 5.0 inches by 1.5 inches
  2. Weight: 1.6 ounces
  3. Temperature range: 30 to 212 degrees Fahrenheit (0 to 100 degrees Celsius)
  4. Plastic probe with 3-foot cord
  5. Suction cup mounting
  • Big, clear display
  • Alert notifications are loud and visible
  • Lightweight
  • Sensitive and fast
  • Accurate
  • You cannot set the alert temperature yourself

If you have a big aquarium and want to make sure that the temperature is balanced and ideal throughout it, this product is a great option. It features a long cord for the probe and is very sensitive as well as highly accurate.

best aquarium thermometer

Buyers’ Guide

What should I look for when purchasing a thermometer for my aquarium?

There are a number of things you can think about and look towards which will help you make an informed decision about what thermometer you should get for your aquarium. Some of the things you should consider are: 

  • Ease of Use and Ease of Mounting

A thermometer has one job and it’s a very simple job: To accurately depict the temperature inside your aquarium. It’s important that a piece of equipment that has such a simple job doesn’t have a convoluted or confusing setup process. 

Most stick-on and analog thermometers are easy to assemble, mount and use. However, some digital thermometers may require calibration or some extra steps which can get annoying. 

  • Temperature Range and Accuracy

You’re investing money in a product that determines whether the living conditions within your aquarium are appropriate or not. Obviously, it’s important that your thermometer be able to accurately tell you the temperature inside otherwise it’s completely pointless and may result in harmful effects for your fish. 

Having a large temperature range can sometimes be helpful. Even though the temperature won’t fluctuate too much in most cases in aquariums, it can be handy to have a large temperature range in the case of a malfunctioning heater.

  • Readability 

It’s important that the temperature has a display that’s easy to read. Big, bold numbers in the case of analog thermometers and backlit displays in the case of digital thermometers are some desirable traits which you should be on the lookout for. It can get annoying if you have to squint and kneel forward every time you have to check the temperature of your aquarium. 

  • Durability 

A thermometer is a piece of equipment which you set up once and then forget about. So, it’s desirable that it works for a long period of time. It goes without saying that the thermometer should definitely be waterproof and you should check it’s build quality to ensure it’s not flimsy or poorly built.

What are the different types of aquarium thermometers? 

Aquarium thermometers come in a variety of functionality, design and styles. Some of the most common forms of aquarium thermometers are: 

  • Digital

Digital thermometers are the ones that can be the most jam-packed with features, however, they are also the costliest kind of aquarium thermometers. 

They often feature a probe on a wire that is submerged into your aquarium water which then gives the reading on the LCD display of the thermometer. This LCD display is often quite easy to read and in costlier thermometers, can also be backlit. 

  • Analog Standing or Floating 

These thermometers look more like traditional ones. They often come with suction cups or magnets that are used to mount these thermometers onto the aquariums. 

They can be fully submerged into the aquarium water or partially submerged. 

These types of thermometers are often inexpensive. 

  • Stick-on Thermometers 

These thermometers employ the use of liquid crystals to determine the temperature of the aquarium water. They are placed on the outside surface of your aquarium and this can be both a good thing and a bad thing. 

It’s a good thing because it’s unobtrusive and doesn’t cause any seepage of harmful chemicals inside your aquarium. It’s bad because there is a chance that it could get affected by air temperature on the outside. 

If you’re going to use a stick-on thermometer, make sure it isn’t placed near vents, heaters, air-conditioners, windows, etc.

How do I use my aquarium thermometer? 

It depends on the type of aquarium thermometer you have. 

Most aquarium thermometers are designed to permanently stay within your aquarium and constantly monitor the water temperature. Some digital thermometers even have built-in alarm systems to alert you whenever the temperature goes out of the assigned safety zone.

If you have a very large aquarium, you can buy several affordable thermometers such as a pack of stick-on thermometers and place them in several different places along your aquarium in order to make sure the temperature is optimal throughout. 

Do I really need an aquarium thermometer?

Yes. It may seem like your fish are having a good time but you definitely need an apparatus in order to make sure they are living at a temperature that is healthy for them. 

Even if your heater comes with a built-in thermometer, it’s still a good idea to invest in a separate, external one since the built-in one could be inaccurate or not functioning properly. 

A thermometer also makes it very easy to maintain water temperatures during tank cleaning and water changes. 

Should I get a wireless aquarium thermometer?

That depends entirely on your setup, your preferences and your resources. 

A wireless aquarium thermometer looks great and is convenient since you don’t want those ugly wires floating about inside your aquarium. However, powering a wireless aquarium thermometer can be a pain as it will require a power source such as batteries. 

Frequently Asked Questions

Where do I put the thermometer on my aquarium?

The placement of the thermometer generally depends on the type of aquarium thermometer you have. Stick-on thermometers are placed on the outside of your aquarium, analog thermometers are fully or partially submerged inside the water of your aquarium, while digital thermometers only have their probe submerged into the water of your aquarium. 

Other than that, it’s important that if your aquarium has a heater or a chiller or any other equipment that affects its temperature, your thermometer should be placed as further away from it as possible so you can ensure that the heating or cooling unit is doing its job throughout the entire aquarium.

How do I use and read a stick-on thermometer?

As we mentioned earlier, a stick-on thermometer utilizes liquid crystals to determine the temperature. Liquid crystals change their color depending on the temperature they’re detecting. 

Stick-on thermometers are placed on the outside walls of your aquarium. 

Start by cleaning the aquarium wall where you’re going to place your thermometer. You can simply clean it using water or an aquarium-safe glass cleaner. Try to avoid making use of detergents or chemicals as things like that should not be brought anywhere near your aquarium as they can have very harmful effects for your fish. Dry the aquarium wall area and stick your thermometer onto it. Make sure it’s free of any bumps before sticking it onto the aquarium wall.

If you’re new to stick-on thermometers, you may be unfamiliar with how they work. They show three readings with three different colors and only one of these readings is the correct one. The green-colored reading is the current temperature, the tan-colored reading is the temperature above it while the blue-colored reading is the temperature below it.

What Should I do if my thermometer detects an irregular change in temperature? 

The first thing you should do is not panic. 

Check your heater to make sure it’s working properly. If it isn’t, replace it immediately or try to fix it if you know what the problem is. 

The important thing to keep in mind is that you should never try to quickly change the temperature in order to bring it back to the optimal level. Fish do not respond well to quick changes in water parameters and sudden changes in water temperature like this could be fatal for them. Try to slowly bring it back to the optimal level.

What are the pros and cons of a digital thermometer?

Digital thermometers have become all the rage these days with everyone gravitating towards them and slowly shifting away from traditional thermometers. 

Digital thermometers are highly customizable and they usually feature a very large temperature range which some may say is overkill for an aquarium thermometer. Some of the more high-end digital thermometers even feature an alert system which can warn you with audible noises and flashing lights whenever the water temperature goes outside of the safety zone. In most digital thermometers, you can assign this safety zone yourself. For the ones in which you can’t, this safety zone is usually between 75 and 82 degrees Fahrenheit, which is the usual optimal temperature for most tropical fish. 

Having so many features and room for customizability means that digital thermometers can often get quite pricey. Other than that, some people may find them overly complex and confusing to operate.

Should I go for a digital or an analog thermometer?

Again, this depends entirely on your situation and your preferences.

If you’re on a budget, we suggest you go for an analog thermometer. However, if you think you can handle the complexity of programming a digital thermometer and are willing to spend the money for a decent one, we recommend you go for a digital one. 

Ensure that if you’re getting a digital thermometer, it’s easy to read. Some digital thermometers come with a display that isn’t backlit and this can be quite a pain to read. 

Final Verdict

With so many different kinds of thermometers available out there, it’s important that you get one that is perfectly suited to your needs as a fishkeeper. 

After rigorous testing, we’ve determined the American Thermal Horizontal Aquarium Thermometer to be the best one out there. It’s easy to use, it has a clear display, it’s highly accurate and it’s extremely fast.

This brings us to the end of our post for the best aquarium thermometers. 

Let us know in the comments what thermometer you’re using for your aquarium.

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