Finding The Best Aquarium Heater Controller

Don’t leave the well being of your fish to chance. Many heaters with built in thermostats fail and get stuck on, frying your fish! Don’t let this happen to you. Protect them with an aquarium temperature controller. 

In this article, I give you everything you need to know and review the top models. And for those of you who want to cut to the chase, our review found the best heater controller to be the bayite Temperature Controller.

In this article we will review the following heater controllers:

To make sure you end up with the right heater controller, read on. 

Benefits of an Aquarium Heater Controller?

What are the benefits of an aquarium heater controller? First and most importantly, they can prevent the catastrophe of frying your fish. Most aquarium heaters have built in thermostats or temp controllers. These are convenient, simple, and inexpensive. But as many people have learned, they can fail. 

When many of these cheap aquarium heaters fail they get stuck in the on position. This means the heater will continue to heat past your set temperature and often exceed 90°F or 32° C . This has resulted in many a fried fish. Yikes! Even the best aquarium heater can fail. 

Aquarium heater controllers are not installed inside the tank but rather externally. The heater still sits in the water but is activated by the controller. If there is a fault with the heating element and the water gets too hot the heater will be shut off. Your water may of course get cold but this is a much better scenario than your temperature shooting up to 90° F!

Other benefits include much more precise and consistent control of your water temperature. Many fish need a very consistent temperature for optimal health. If you have a cheap heater with a built in thermostat your water temperature may swing as much as 2 or 3 degrees. A good external heater controller will keep it within a much closer tolerance. 

Many aquarium temperature controllers also come with audible temp alarms. If the water gets dangerously cold or hot the alarm will sound. This can be a lifesaver for your fish. 

The Best Aquarium Heater Controller

This inkbird is an affordable 2 stage heating and cooling controller. The 2 stage feature allows you to protect your aquarium from temperature drops as well as spikes. 

This configuration has two sockets. One is labeled heating where you plug in your heater. The other is labeled cooling and this is where you plug in your chiller. To control these you simply enter in your low and high set points in the controller and it does the rest.

While the provided manual is adequate, the settings can be a little complicated. So don’t misplace that quick reference guide, you will need it! To save you my frustration remember to hold down the “set” button for at least 3 seconds or the unit will not save your entries. 

This controller also has an audible alarm that will sound if your set temperatures are exceeded. This may occur if your heater or chiller fails, in which case immediate action will be needed!

A word of caution for the those of you with a saltwater or reef tank. The provided stainless steel temperature probe will eventually corrode and fail in saltwater. Fortunately, Inkbird makes a corrosion-resistant replacement probe. Some have also had luck coating the provided metal probe with aquarium sealant. 

Overall, the ITC-308 is a reliable, inexpensive option for those in need of a dual-stage controller. There is also a WiFi capable version for those of you so interested. 


  • Affordable
  • 2-stage heating and cooling control
  • Audible alarm sounds when set temps are exceeded
  • WiFi capable option


  • Provided stainless steel probe not suited for marine aquariums
  • Settings can be complicated

If you don’t need a two stage heater controller and just want something to run your aquarium heaters this is a solid choice. It comes with a dual outlet plug so you can hook up multiple heaters and it is rated for up to 1200 watts. 

The easy to read LED screen displays current and set water temperature. It is important to note that the unit operates in whole degrees instead of fractions of a degree. For example, it can be set for 78° or 79° but not 78.5°. This also means that the temperature of the water must drop 1 degree below your temperature setting before the heater is activated. Some people prefer more granular control but I have found that this isn’t an issue for most. 

The ITC-306T can also be set up for a dual time cycle. This allows you to set a different daytime and nighttime temp. While this is a neat feature, most aquarists won’t have a need for it, but it’s there for those that do. 

Some people including myself find the codes for the control settings to be a bit complicated. Fortunately, the directions are fairly easy to read and do a decent job at explaining the process. 

Like most aquarium heater controllers the temperature sensing probe is the most common point of failure. If your unit is not functioning correctly it is most likely this component. Fortunately, it is very easy to replace the probe and they can be easily sourced. I recommend being prepared and purchasing a replacement probe right off the bat. 

This unit is an easy choice for most aquarium set ups. It’s affordable, popular and gets the job done


  • Affordable choice for most aquariums
  • 1200 watt heater capacity
  • Easy to read LED screen
  • Simple single-stage heating control


  • Set up can be complicated
  • Temperature probe is prone to failure

The Finnex Heater Controller is a single stage controller which means it heats only. It is rated for 800 max watts but it’s best not to push this wattage rating. For those with smaller aquariums this is plenty of power but there are those of you who will need more. 

This is a pretty straight forward aquarium heater controller. It is easier to program than some of the other controllers. It also holds the water temperature stable with little variance. If the temperature becomes unsafe it has an audible alarm to alert you. 

The downside is that some of these units haven’t been calibrated correctly at the factory. There are also no instructions or option to calibrate it yourself. If you get one of these units the only reasonable remedy is to adjust the temp setting above/below what you want to get the actual water temp you need. It generally works just fine once you get it dialed in but this does annoy me a bit. 

Another thing that you should be aware of is the short temp probe cord. It is no more than three feet long which does not give you a whole lot of options for mounting the controller. But, unlike other heater controllers, this one has a plastic probe instead of metal. This means it will be more resistant to corrosion and failure so it should work in your reef tank. 

This is a quality unit and you don’t need to buy a separate corrosion-resistant probe.


  • Holds temperature very stable
  • Rated for up to 800 watts
  • Easy to program
  • Plastic corrosion resistant probe


  • Temperature calibration issues
  • Temperature probe cable is too short

Top Pick!!

I have to say, I am impressed with the bayite Temperature Controller. Especially considering it hits the same price point as other affordable controllers. 

There are two models of this temp controller depending upon how much power you need. The BTC201 is rated at 1100 watts and the BTC211 is rated at 1650 watts. Aside from the power ratings, these two units are exactly the same. 

The bayite Temperature Controller is a dual-stage heater controller. While it is designed to heat and cool it can also be used as a single function controller. It also has an audible high and low-temperature alarm which can be a lifesaver for your aquarium. 

Setup is complicated and not very intuitive, however. Instructions are not the best but will give you the info you need. Just plan on spending a little time to get it set up. Or skip the headache and check out this YouTube set up video.

One of the areas that this controller outshines the Inkbird controllers is that you can fine tune the temperature to tenths or 0.1 degrees. Other controllers are only adjustable by whole degrees. This means that the unit will keep a tighter temperature range than other units. It also stores your temp settings if it loses power for whatever reason. 

Be aware that the provided temperature probe is not corrosion-resistant. There is a corrosion-resistant probe available though. It may require some hard wiring on your part but it is far superior to the provided probe. 


  • High/Low temperature alarm
  • 0.1 degree fine tuning and response
  • Dual stage
  • Stores settings if power is lost
  • Affordable


  • Set up is complicated
  • Temperature probe is not corrosion resistant

Best aquarium temp controller?

So which is the best temp controller for your fish tank you may ask? The Inkbirds are good but for my money, I’m going with the bayite temperature controller. It has the same features as many other controllers to include temp alarm, dual-stage, and an affordable price point. Beyond that, though it allows finer tuning to 0.1 degrees rather than whole degrees. It also saves your settings if unplugged or without power.

I recommend this controller with one caveat. If you want to get the best reliability out of this controller make sure you buy a corrosion resistant probe.

How to get the most out of your heater controller

Aquarium temperature controllers are a great tool in your aquarium arsenal. There are a few things you should know to get the most out of your unit. 

Power or Wattage Rating

First and foremost, make sure it is rated for enough wattage to power your heaters or chillers. All heaters or chillers should come with wattage printed on the package or in the manual. 

It is always best to have more capacity than you need rather than pushing the controller to the limit. For instance, if your temperature controller is rated for 800 watts its best not pair it to your 800-watt heater. It would be better to have something that is rated for 1000 or even 1200 watts in this instance.

Having a wattage buffer will prevent issues with power spikes and so on.  

Control Unit Mounting

You’ll want to consider where you’re going to mount your controller before setting it up. To put it simply, mount the control unit away from humidity. One of the benefits of using an aquarium heater controller is that the thermostat isn’t located in the moisture and humidity of the aquarium. This makes it less prone to failure. 

So make sure it isn’t mounted directly above or near the top of your aquarium. Place it somewhere away from your aquarium and mount it securely so it doesn’t get dropped. 

Probe placement

The probe is what reads the temperature of your water in the aquarium. In order to get the most accurate reading possible, placement is important. 

The worse place to put your probe is near the heater. This will cause it to read a higher temp than it should. Place it far away from the heating element in a place that gets some water flow. 


It goes without saying that you should calibrate your temperature sensor right away. Many times they aren’t calibrated accurately right out of the box. Some temperature controllers have a digital calibration function while others do not. Make sure to follow the directions provided if yours allows for calibration.  Verify the temperature with an accurate thermometer.  

If you are not able to digitally calibrate your controller there is another option. You can adjust your set points to compensate accordingly. For instance, you may have a controller unit that consistently indicates 2 degrees higher than the actual temperature. To correct this you can set your desired temperature 2 degrees high on the controller to compensate. 

How Does an aquarium heater controller work?

An aquarium heater controller is made up of three basic parts. The controller unit, the socket, and the temperature sensor probe. These three components work in harmony to keep your water temp at your set preference. 

Single Stage or Dual Stage?

There are two basic types of aquarium temperature controllers. Single-stage and dual-stage. A single-stage controller performs one function. It heats your water to a set temperature and then it turns the heater off. This is generally enough for most people and aquarium set ups. 

But what if you are also worried about the temperature getting too hot?  You may have a lot of money into your aquarium livestock and want to take every precaution.  This is where dual-stage temperature controllers come in. 

Not only do you set a minimum temp, but also a maximum temp. If the water in your fish tank drops below your set temperature the heater is turned on. If the temp goes above your temperature setting it activates your water chiller. 

Controller Unit

The controller is the brains of this whole operation. This is what reads the water temperature and is programmed to keep it in a certain range. These have large LCD screens and various buttons you use to program the unit. 

There are different variations of controller units depending upon the model, but they generally all work the same. Differences are usually single stage or dual stage, whole degrees or tenths of a degree and temperature alarms. 


This is the outlet where you plug in your heater and/or chiller. A single-stage or heating only controller will have one or two outlets that you can use to plug in your heater(s). A dual-stage will have two outlets with one labeled heating and the other cooling. 

Temperature Probe

The temperature probe is the component that senses the temperature of the water. The sensor end is placed in the water and the other end is plugged into the control unit. 

This component is the most common point of failure with any aquarium heater controller. The metal tip can corrode and if it isn’t sealed correctly water will get into it. While this can happen in freshwater aquariums it is especially a problem in marine or saltwater aquariums. 

This will cause the controller to read the temperature incorrectly.  If it isn’t producing an accurate temperature it can over or under heat your aquarium. When this happens many people assume that the whole unit is defective and throw it out. The simplest and easiest solution is to simply replace the probe. 

To prevent this issue you can often purchase a corrosion-resistant probe. Just make sure that it is compatible with your controller or that you can hardwire it. You could also go the DIY route. Some people have had luck sealing the stock probe with aquarium safe sealant.