Disclaimer: This page contains advertisements and/or affiliate links. We receive compensation from clicks and/or purchases made through these links. Though we may not have tested the specific product(s) mentioned, we do our best to recommend products that are beneficial to our visitors.
What Heater Do I Need for My Aquarium?
Last updated on November 17th, 2023
Do you need a fish tank heater?
A saltwater fish tank heater is among one of few REQUIRED pieces of aquarium equipment required for a successful saltwater aquarium. Similar to salinity, temperature is a key parameters to keep stable, as it affects everything within the saltwater aquarium. If your temperature varies more than about one or two degrees F throughout the day, it can cause stress on fish, coral, and invertebrates in the fish tank. Stress can then lead to slowed growth, poor coloration, illness, or even death. So in short, the fish tank heater is not only necessary, but one of the most important pieces of equipment for the reef tank.
Saltwater Fish Tank Heater
A quality fish tank heater is vital to your saltwater tank. Marine life is frequently from warm water, meaning you will almost always need to heat your tank, unless you live somewhere warmer than the tank needs, in which case, you may need a chiller. The ideal temperature for saltwater fish tanks is between 75 and 82 degrees Fahrenheit. More importantly, the temperature should stay within one degree of whatever temperature you choose, and not sway throughout the entire range. You will need to research the ideal temperature for your saltwater fish tank based on which fish, invertebrates, and corals you plan to keep. A good starting point to target is 79-80 degrees as this is a middle ground that will support most life.
For a quick introduction into the saltwater fish tank heater, watch this short video from Marine Depot.
Types of Fish Tank Heater
If you've been searching for a fish tank heater, I'm sure you noticed there are a variety of different types. Some with built in temperature control, some made of glass, some titanium, and some fish tank heaters are made of plastic. Which saltwater fish tank heater is best?
Glass Fish Tank Heaters
The Glass fish tank heater is the baseline standard for the saltwater fish tank hobby. Most glass fish tank heaters are submersible, so they can go entirely under water. They are usually the cheapest saltwater fish tank heater available, and work well for most people. So if the glass fish tank heater works well and is cheap, why look at other types of fish tank heaters? That's simple. They're glass. When a rock falls on it or it comes out of water while still hot, they shatter. Not only does this leave broken glass your tank or sump, but it will almost always lead to electrocution as well. Though glass fish tank heaters work from an equipment standpoint, I generally avoid them from a safety standpoint, mostly because I've had 2 or 3 break while doing water changes.
Titanium Fish Tank Heaters
The titanium fish tank heater is generally also submersible, and in most ways, identically to that of the glass fish tank heater. There is one major difference though, the titanium fish tank heater doesn't shatter! If a titanium fish tank heater is run out of water for a short period of time, it may burn out, but there is no broken glass nor probes in your tank to electrocute you! That being said, titanium fish tank heaters can "pop" if they are run too long out of water or longer than their life expectancy. These fish tank heaters do cost slightly more, but when it comes to saltwater fish tanks, it's worth the extra money for the safety factor and one less thing to go wrong. My personal favorite titanium fish tank heater is the Finnex analog titanium fish tank heater as the setpoint does not reset after a power outage.
Other Fish Tank Heater Types
Though there are other, better types of fish tank heaters available, such as the Cobalt Neo-Therm Fish Tank Heater, they are generally significantly more expensive and only found in small sizes. These plastic fish tank heaters are safer than titanium aquarium heaters, however the titanium heater is already so durable, the extra cost does not make much sense.
Built-in temperature control
Many fish tank heaters come with the option of a built in temperature controller or thermostat rather than being preset. Giving you the freedom to choose the temperature you want your aquarium water to be. In general, it is not wise to rely on the temperature sensor built in to the fish tank heater. This is because they're not overly accurate as well as being too close to the heating element to accurately measure the temperature of the aquarium water.
Though contradictory to the previous statement, I recommend getting a fish tank heater that includes this built in control as it gives you the freedom to set the aquarium temperature, which is not provided by the preset fish tank heater. Additionally, if you use a saltwater aquarium temperature controller, it provides a backup shut-off. In case the temperature controller gets stuck on, the fish tank heater's built in thermostat can turn off the fish tank heater a couple degrees higher than the external controller. This removes another layer of risk from your saltwater fish tank.
Heating Your Aquarium with Gas (Water Heater)
To start, this only really makes sense if you are currently using about 1000 watts or more to heat your aquarium. Usually a minimum of 500g or so. If that is your situation, you should read my article about How to Heat and Aquarium with Natural Gas.
Temperature Controller for A Fish Tank Heater
Regardless of whether you use a preset fish tank heater or a heater with a built in temperature controller, it is recommended to get a separate temperature controller. Having a separate aquarium temperature controller allows you to have a more accurate reading on the fish tank temperature as you can place the sensor near your return pump or even in the aquarium itself. Some aquarium temperature controllers even have WiFi connectivity to inform you if something is wrong with the aquarium's temperature.
Best Aquarium Temperature Controllers
Saltwater Fish Tank Heater Watts Per Gallon
Despite what many sites may claim, there is no exact answer to this question. The fish tank heater watts per gallon depends on the size of the tank, the turn over rate of the tank, and the difference in temperature between the room and the water.
Well that doesn't seem useful, does it? I'm sure you just want a number, right? I have found, as a rule of thumb. It is best to start with 3 to 4 watts per gallon of water in the entire system (tank + sump), then round to the nearest available fish tank heater size. For example, if you have a 50 gallon aquarium, you would want 150 to 200 watts worth of fish tank heaters. Ideally, this wold be split to use at least 2 fish tank heaters as a safety measure. Meaning the best fish tank heater in this case, 2-100 watt fish tank heaters with an aquarium temperature controller.
How Often Should I Replace my Fish Tank Heater?
The saltwater fish tank heater is one of the most important components to the health and success of the aquarium. That means that you do not want to risk the fish tank heater failing at any time. To prevent this risk, you will want to replace the fish tank heater before anything goes wrong. How often should you replace the fish tank heater if you can't tell when it will fail? With the low cost of these fish tank heaters, I strongly recommend replacing all fish tank heaters once per year.
A good rule of thumb is to pick a holiday, frequently the new year, and do any major equipment replacement at that time, including the fish tank heater. This acts as a constant reminder as well as let you start the year on a positive note.
Recommended Saltwater Fish Tank Heaters
At the end of the day, there are two fish tank heaters I recommend. I personally prefer the safety of the analog controlled titanium fish tank heater, but for those of you that prefer digital, Finnex offers a digital version of the Titanium fish tank heater as well.
- Finnex Analog Titanium Fish Tank Heater with Built-In Controller
- Finnex Digital Titanium Fish Tank Heater with Built-In Controller
In addition, I STRONGLY recommend a fish tank heater controller such as the InkBird Temperature Controller.
The fish tank heater is one of the most important components for reef tank success. Maintaining a temperature of about 79-80 degrees F and maintaining the temperature within 1 degree F is strong start toward reef tank success! Picking a fish tank heater with 3-4 watts per gallon of water, and splitting that across at least 2 fish tank heaters, will give you a backup in case of failure. Even more important is adding a fish tank heater controller to make sure your aquarium doesn't overhear nor cool down too much. Follow the rules laid out in this post and you will be off to a good start in terms of the fish tank heater.
About the Author
John is a Software Engineer with a passion for saltwater aquariums, as well as the founder and president of Reef Stable. He started in the aquarium hobby as a child with a 20 gallon freshwater aquarium. His interest in aquarium life grew and in 2008, John set up his first saltwater aquarium.
Today, John maintains an over 300 gallon reef tank system, consisting of a 120g reef and a 210g reef. These large tanks are contained within the same system, sharing a sump as a means to reduce total maintenance and increase total water volume.
John writes articles for the blog as a means to learn about more reef aquarium topics. These articles act as a reference for the readers as well as himself. John updates these articles frequently to provide additional information or make corrections as new information becomes available.
If you would like to request an article, tank tour article, or to collaborate, let me know via the Contact Me Page!