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When you’re thinking about all of the items you need for your aquarium, you may have overlooked one small but crucial device, the thermometer! Depending on what you keep in your tank, type of fish and plants, water that becomes unsuitable could have detrimental effects. Changes can happen even when everything appears to be just fine.
We recommend using a thermometer for any tank you have, to track water changes over different days and times and to help correct any issues that come up. If you run a quick search for aquarium thermometers, you’ll find that you come up with a ton of conflicting and hard to sift through information.
There are three basic types of thermometers for tanks. Each is great for different things, models, and sizes of aquariums. The bottom line is that you need one and you should be recording water temperatures regularly. Doing so will help ensure that the temperature of the water is stable and staying within the optimal range for the type of fish you keep.
1. What kinds of thermometer are there?
The three types of thermometers are digital meters, stick on the outside meters and standing/floating in water meters. For each type of thermostat, there are a few subtypes. Each has its own set of pros and cons.
The various types of thermometers will be better suited for aquariums of different styles and sizes. We’re going to give you a quick rundown of the pros and cons of the three main types of thermometers along with the pros and cons of each. Then we’ll get into our round-up of the best of each kind.
2. What are the pros and cons of digital thermometers?
This kind of thermometer is made up of a probe that you set inside the tank that is connected to a digital display, kept outside of the container. The probe can be either temporary or permanent. You can also find those that are wireless and those that connect with a cord.
In general, you’ll need batteries for these to run on, though there are some that also plugs into the wall for power. Unfortunately, some people aren’t fond of the unsightly cord that runs between the probe and the display as there isn’t much that can be done to hide or cover it.
You’ll find that several models include a display that can be kept inside the tank as well, but you run the risk of the batteries leaking into the water at some point. There are also several models that allow for an audio alarm should the temperature rise above or fall below the desired temperature range.
At the lower end of the price scale, you may not get a digital thermometer with this alarm; it features an alarm on some of the higher end models. When purchasing a digital device with a probe, check for the length of the chord so that you aren’t stuck with a product that doesn’t work out with your set up.
3. What about the kind you stick on the tank (LCD)?
You will find this to be a very commonly found thermometer when it comes to tanks and aquariums as they are often purchased as part of a set. The LCD stands for liquid crystal display and can sometimes be called “digital” meters although this is not entirely accurate.
When purchasing this type of meter online, you want to ensure you aren’t buying one of these lower cost thermometers in place of the more accurate, often battery powered digital display meters. These LCD meters are stick on and are meant to stick on the outside of the tank.
Due to their placement, some argue that ambient room temperature can affect the reading, though the consensus is that they are accurate enough for general use. They’re also the least expensive and considered highly versatile.
You can find them both with a single scale of that is easier to read numbers and those with dual scales of Fahrenheit and Celsius. You’ll notice that various models may include different temperature ranges so be sure to check the label before making your purchase. Most tend to be prepared for vertical reading while others have a horizontal display.
If you choose this type of meter, you want to ensure placement away from any heating/cooling vent, and out of direct sunlight. Installation should remain above gravel level for accurate readings and read from straight on. If you have to bend or twist at all to see the monitor, it’s not a suitable placement.
4. Are standing or floating thermometers any good?
This type of monitor is placed inside the tank, giving the reading a more direct measurement of the water. There are several styles and designs for this type of thermometer.
You will find those that hang on the inside of the tank by the clip, those that suction cup to the side of the tank, and those that float inside the container. You can also find a weighted kind that will stand at the bottom of the tank once it sinks.
These types of thermometers may not be suitable for individual fish that are large or behave wildly in the tank. They also tend to have much smaller numbers for reading making a quick temperature gauge tough to do.
One of the positives of this type of meter is that they generally include a colored scale on the back indicating whether or not water temperature is within a safe range. If you have a large tank, you can place more than one of these inside the container at opposite ends, or one is floating and one sinking.
How Much Can You Expect to Spend?
Owning an aquarium with wildlife, plants, and fish can sometimes become an expensive hobby. We understand you may be worried about how much you’ll spend on this little necessary gadget, but honestly, you shouldn’t sweat it. You can get a thermometer for as low as $3 to $10, but some of the most expensive products you’ll find can be up to $20.
How We Reviewed
Because certain types of thermometers are best for certain types of tanks based on style, size, and fish/plant life contained, we looked at which thermostats consistently provided accurate results, were durable, could face normal wear and tear, were easy to use and more. Be sure to skim our reviews of each product we found to be the best of its kind for details on why it was the top pick!
Our Top Picks
- Submerge probe into fish tank to measure water temperature (Submerge probe only, do not submerge thermometer in water).
- Easy to apply suction cup and easy to read lcd screen; temperature readings to within 1 degree
- Large, easy to read lcd display; compact design for discrete use
- Temperature range -50 degree Celsius ~ + 70 degree Celsius; Operating temperature -10 degree Celsius ~ +50 degree Celsius.
- Powered by one lr44 button cell (included)
This digital meter comes with the submergible probe with a display that on the outside of the tank. We love that it’s inexpensive. The screen is easy to read, the suction cups are strong enough to keep it in place, and it has a decent temperature range.
It needs just one lr44 cell battery, which you'll receive with the product. We found the temperature readings to be steady and accurate to within 1 degree. The chord is approximately 40 inches from end to end, and it does not include an alarm.
Rating: Other consumers loved this meter, rating it at 4.5 out of 5 stars.
- TEMPERATURE - Temperature range is -20℃ ~ + 70℃. Temperature accuracy is ±1℃(±2℉). Update measured temperature every 10 seconds.
- READINGS - LCD screen displays measured temperature which can be switched between ℃ and ℉, and it can save the maximum and minimum readings during past tests.
- SCREEN - Large screen displays clearly, no dead corner on the left or right make it looks more beautiful. Besides, if you want a clearer screen displays, you can remove the screen protector.
- INSTALLATION - Easy and convenient to install at fish tank with suction cup or spring clip that make sure space-saving and portable. You can put this small thermometer at anyplace you want to place. (Please only submerge probe, don't submerge thermometer in water)
- MATERIAL - Eco-friendly ABS shell which is tough and hard. Excellent mechanical properties make the device safer, wear-resistant and stable. High accuracy with professional sensor, it can measure temperature more correctly than same product. Powered by two AG13 button cells (included).
This digital monitor has an impressive large screen with easy to read display. It also reads the temperature every 10 seconds for an accurate reading. It comes with an excellent temperature range though a little smaller than the Zacro mentioned above. It can be attached to the tank with a spring clip or a suction cup easily.
Its durable outer shell makes it durable, and it comes with the two AG13 button cell batteries it needs for power.
Rating: Consumers approve of this product, rating it a 4.1 out of 5 stars.
Whether you’re just getting started or wanting to replace your current stick on meter, this is a great choice. It comes with a vertical reading scale. Other consumers found that it had accurate readings on glass, acrylic and plastic tanks of varying thickness.
The size is approximately five ¼ inches by ¾ an inch. Be sure to read the pamphlet it comes with as it will explain the different colors and how to read an exact temperature.
Rating: Consumers are generally happy with this product, giving it a rating of 4.5 out of 5 stars.
- Made in the USA - Includes 2 Thermometers
- Immediate response, Intuitive, Accurate
- Easy to read red display with no confusing multiple colors to interpret
- Self-Adhesive and moveable. Measures 5 inches tall by 1/2 inches wide
- Temperature range 58°- 88° F (14°-31° C)
Prairie Essentials provides a great product. The thermometer has a reasonably easy read on it, that doesn’t come with multiple colors – which can be a drag for some people.
Each monitor is about 5 inches by a half inch wide, with a broad temperature range. In case you’re a fan of the dual measurements, this one only comes with the Fahrenheit reading.
Rating: Tons of positive reviews from consumers leave this monitor ranking with a 4.5 out of 5 stars.
- Made of glass, small size and ultralight
- It floats and is secured by a included suction cup
- Easy to install, just drop it in the tank and attached the suction cup to the inside of the tank for easy and accurate reading
- Clear and easy to read scale that tells you, unmistakably what the temperature is in both Celsius and Fahrenheit degrees
- Being that this thermometer is inside the tank, it gives a much accurate reading of the water temperature than those placed on the outside
This ultralight, glass meter is small and suction cups to the side of the tank to keep it in place. It’s called a floating thermometer, but it stays in one place. It reads with both a Celsius and Fahrenheit scale, clearly and easily. We found the reading to be steady and accurate, as it sits inside the water.
This meter works well in tanks ranging from sizes of 10g up to 150g, with accuracy. You may want to consider that because it only suction cups at the top, the bottom of the meter can tap against the class as the water moves.
Rating: Consumers considered this to be an inexpensive, effect device, rating it at 4.5 out of 5 stars.
- Weighted aquarium thermometer
- Fits securely in gravel
- Unique anchoring fins Will not shift positions
- Green safe zone indicates optimal temperature range
For those looking for a weighted thermometer that sits at the bottom of the tank, this is the one for you. As you know, having the thermostat too close to the bottom of the container can make the reading inaccurate, but that was taken into the consideration of the design.
The monitor is weighted and comes ready to sit snugly on top of the gravel. It also has an easy to read, colored, “safe” zone for quick and easy reading.
Rating: Consumers who purchased this device for their aquariums, were generally happy, rating it a 4 out of 5 stars.
All of these meters are excellent and useful devices. But we don’t love the suction cups used in floating thermometers or the sound of the instrument tapping the glass. We’re also not in love with adhesive thermometers because, well, the adhesive! We always revert to the digital meter, and we love the Zacro LCD Digital Aquarium Thermometer.
It's easy to use, easy to set up, and always gives a clear, accurate reading. The chord can be a bummer for some, but we didn’t have any issue coiling it up and hiding the excess behind the tank. It’s a safe, effective, and inexpensive monitor to choose.