How to Install a Heater in Your Aquarium
Aquarium heaters are one of the most critical components of your tank's life support system. Not only because they maintain stable water temperatures, but also because they are trusted to run quietly in the background, 24 hours a day, protecting your fish, corals, and invertebrates from sudden temperature swings.
A properly installed heater helps prevent stress, illness, and even loss of livestock. In this guide, we will walk through exactly how to install an aquarium heater the right way, so you can be confident your tank stays safe, stable, and ready to thrive.
How To Choose the Right Heater
There are three common types of aquarium heaters on the market, all of which can work to maintain stable water temperatures in both freshwater and saltwater aquariums.
- Preset Heaters - Preset at a specific water temperature and cannot be adjusted. Often made of glass and will be your most affordable option.
- Internal Thermostat Heaters - Feature an integrated thermostat that can be adjusted to your desired water temperature. Usually glass but sometimes high-density plastic, Pyrex, or even titanium. Easiest setup and best value considering the adjustability and still relatively affordable in most cases.
- Heating Elements - Usually made of titanium and do not include any built-in temperature control. A reliable temperature controller is required for proper function. While this is the most costly option, it is also the most reliable. The modular nature of the system means you can replace the heating element, temperature probe, or controller individually.
You want 3-5 watts of heating power per gallon of aquarium water. For a 20 gallon tank, thats 60 - 100 watts of heating power. You can split this up between two heaters for a dual heater setup or just use one heater but either way, don't go with the bare minimum or else your will most certainly run in to premature failure.
What Is a Temperature Controller & Do I Need One?
A temperature controller is a device that monitors your aquarium’s water temperature and automatically turns your heater or cooling equipment on and off to keep the tank within a safe, stable range. Instead of relying solely on the heater’s built-in thermostat, a controller adds an extra layer of protection by acting as the “brain” that decides when heating or cooling should happen. This greatly reduces the risk of common heater failures, such as getting stuck in the “on” position and overheating the tank.
While a temperature controller is not strictly required to run an aquarium, it is highly recommended for anyone who wants added peace of mind, especially for tanks with valuable fish, corals, or sensitive species. By maintaining tighter temperature stability and providing fail-safe protection, a controller helps create a safer, more consistent environment that supports long-term aquarium health.
We are not shy about our affinity for the InkBird Wifi Temperature Controller because it has the ability to send push notifications to your smartphone after connection to your home Wifi network via the InkBird app. That means you can be notified to take action when something goes wrong, even if your not home. Additionally it has redundant dual relays, two replaceable temperature probes, and an audible alarm with a high, low, and continuous heating time alarm.
Learn more about the InkBird Temperature Controller with Thomas on BRStv
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There are a couple of options for configuring a standard heater install. Forgive me for the simple diagrams, its just too much fun working with AI generated images.
- Configuration #1 is for heaters with built in temperature control. Simply add the heater to the aquarium or sump in a safe location and plug it into the wall socket.
- Configuration #2 displays how to install a temperature controller and heater together. The temperature controller plugs into the wall and your heater plugs into the socket on the controller.
How To Setup Your Aquarium Heater Step-by-Step
1. Choose The Right Location
Place your heater in an area of the sump or all-in-one aquarium where the water level stays consistent and flow is steady. Avoid return sections or any chamber where the water level can drop with evaporation, since exposing a heater to air can be dangerous. Skimmer section in your sump or one of the dedicated filter chambers in your all-on-one aquarium is best. You can install directly in the display aquarium as well but use an appropriate heater mount.
2. Place the Heater, But Do Not Plug It In Yet
Submerge the heater and let it sit in the water for 15 to 30 minutes before powering it on. This allows the heater to acclimate to the tank temperature and helps prevent damage, especially with glass heaters. Secure it using the included suction cup mount or sturdy heater mount so it never rests directly against glass or acrylic.
In a sump, fully submersible heaters can be mounted horizontally under the water as opposed to a vertical mount like you might do in an AIO or display aquarium.
3. Install the Temperature Controller and Thermometer
Position one temperature probe before the heater and one after it to monitor both incoming and heated water. Plug the heater into the controller’s heating outlet, then plug the controller into a wall outlet or power strip. Make sure all cords have proper drip loops for safety.
Secure your controller display in a safe location, away from moisture and in a reasonably easy to access location. You do want to be able to easily glance at the aquarium's water temperature when walking by your tank on a regular basis. If you can't easily see the display, there is a good chance you won't monitor it.
It is a good idea to install a seperate thermometer with a large, easy to read display, directly in your display aquarium where you can easliy see the display at a glance.
4. Set Temperature Controller & Heater Temp
The controller will only allow power to the heater when water temperatures drops below your target temperature. Your controller will be your primary switch for turning the heater on and off.
- The controller should be set at your target temperature, lets say 78°F. InkBird controllers are factory set to 78°F which means, for the most part, you won't need to change any settings right away.
- If using a titanium heating element or preset heater, there is no further adjustments required. If your using a heater with a built-in thermostat, set the thermostat on your heater to be appx. 1-2° F above the temperature controller setpoint (79°-80° F. )
5. Verify & Calibrate Your Temperature Controller
This step is often overlooked or skipped. Verify the controller reading matches the water temperature you get with a seperate thermometer. Of course, a decent quality thermometer that is calibrated out of the package is required to complete this step effectively. The InkBird has a calibraiton feature so if you do see a consistant variance, you can adjust the temperature reading on the controller to match your thermometer.
Once calibrated, verify the heating element is turning ON and monitor water temperature as it heats up over the next few hours. Stay close to the aquarium as you want to also verify the heater turns OFF, when target temp. is obtained.
Redundancy, Redundancy, Redundancy
As ol' Ben Franklin said "To fail to plan, is to plan to fail". You can choose to do the bare minimum or do everything possible. Regardless, every step you take to protect your aquarium against a heater failure is time and money well spent.
- Keep a spare heater on hand at all times - this way you have something on-hand if you find yourself in a pinch. Get something with a built in thermostat like the Eheim Jager or AquaReady preset so your prepared for a heater and/or controller failure.
- Use two heaters - remember how the Inkbird Controllers feature dual power sockets and dual relays? Thats because its best to use two heating elements simoltaneously. Not only will you heat the water faster, but your will have at least one working heater in the event one fails! Should one of the relay switches fail, there is a backup ready to go and keep both of your heaters running smooth.
- Add a Neptune Systems Apex Controller which has a temperature control feature plus monitoring, alerts, and so much more! You simply plug your Inkbird into the Apex Energy Bar and program it to cut OFF power in the event water temperatures rise to dangerous levels. Conversely, you can set the Apex with your target water temperature (primary switch) and set the temperature controller as your back-up switch with a higher setpoint. Either way, you folded a third layer of redundancy...or is that 4 layers?
Did You Know? The most equipment related failures are related to the heater. Specifically the temperature control or built-on thermostat inside traditional aquarium heaters. The dual-relay components in your Inkbird and the relays inside the Neptune Systems Energy Bar are more robustand reliable than the built-in thermostat of a traditional aquarium heater. This is why we recommend using the controllers as your primary switch device. It is less likely to fail or at least, will last much longer than the control components inside your heater.
With over 25 years of experience keeping aquariums of all kinds, Robert has a detailed understanding of advanced aquarium techniques and theory. Working as a professional content creator in the saltwater aquarium industry for over 18 years, his perspective, thoughtfulness for the hobbyist, and a general understanding of the hobby, and industry that surrounds it, allows Robert to write and create digestible content that makes reefing fun and easy.
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