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Q11198 - INFO: Everything You Ever Wanted to Know About Aquarium Heaters By Keith MacNeil, Reef Squad
As the winter months draw near, colder temperatures—both inside and outside—are fast approaching.

It's around this time each year I begin to see threads pop up on aquarium message boards discussing aquarium heater failure. Sometimes hobbyists are lucky: the heater simply did not turn on and their tank got colder. In other instances, heaters actually overheat or crack and the results are disastrous. I actually experienced heater failure myself this past season. I got lucky: my heater only stopped working, so the tank temperature dropped a bit. Fortunately, I had a spare heater on hand to take its place.

Unfortunately, dealing with heater failure is an inevitable part of caring for a temperature-sensitive aquarium system. If we keep that in mind—that aquarium heaters can and will, eventually, fail—we can prepare accordingly to protect our precious pets from temperature fluctuations.

With that mindset in place, you may be asking yourself, "What can I do to protect the livestock in my aquarium?"

ViaAqua Titanium Heaters
ViaAqua Titanium Aquarium Heaters
Here are some tips to help you safeguard your aquarium from heater failure:
  • Research the various aquarium heaters available for your tank. Nearly all the heaters on our website have customer written reviews about their performance. This feedback is invaluable when making a purchasing decision. Starting with a high quality heater minimizes the chance of failure. To help your search, we've listed our top 10 best-selling heaters at the conclusion of this article.
  • Once a heater is set up, there really isn't much maintenance involved with its upkeep. Make sure the heater is functioning properly (turning on and off), is free of build up and doesn't show wear on the electrical cords.
  • If you are setting up a new aquarium, allow 24-hours for the water to adjust to the temperature you selected on your heater.
  • Use a temperature controller (or system controller) to turn the heater on and off. While most heaters have built-in thermostats to turn the heaters on and off, many times this is precisely what causes the heaters to fail. The thermostats "stick" in the on or off position and the heater will not properly energize or de-energize. A temperature controller will turn on/off the heater independent of the thermostat built into the heater.
JBJ True Temp Digital Controller w/ Heater
JBJ True Temp Digital Controller w/ Heater
  • When using a temperature controller in combination with a heater that has an analog dial thermostat temperature setting, set the temperature on the controller a degree or two cooler than the thermostat on the heater. That way, in case the controller fails to shut the heater off, the heater's thermostat will shut it off. If your heater has a digital display (LED, LCD, etc.), use your controller as the backup and set the controller's shut off point a couple of degrees higher than the heater's controller.
  • Consider using multiple heaters instead of a single heater. If your tank requires around 500 watts of heating power, try using two 250 watt or three 200 watt heaters. This will help in a couple of ways. First, if one heater fails, you have a back-up heating the tank. Second, if a heater gets stuck in the on position, it will raise the temperature more slowly than a single larger wattage heater, hopefully allowing you time to catch it before larger problems arise.
  • Heater placement is also very important. Knowing that heaters can fail, don't hide the heater underneath a pile of rocks that could make it difficult to excavate in the event of failure or make it impossible to visually inspect it. You also want to provide good water movement around the heater to allow for the heated water to circulate throughout the tank. If you have a sump on your tank this can be an ideal location for the heater.
Fiji's Best Saltwater Aquarium Live Rock
Fiji's Best Saltwater Aquarium Live Rock
  • Protect glass heaters from falling rocks or other objects/livestock that might cause it to break. This is especially true in tanks with larger, predatory fish. It is highly recommended to take precautions with heaters in these types of tanks.
  • Titanium heaters can get hot enough to melt acrylic, so never put a heater directly against an acrylic tank or sump.
  • Don't trust with 100% accuracy the dial on a heater's thermostat. Heaters will sometimes heat accurately, but the temperature may not match the numbers on the dial. Use your thermometer(s) as your reference and set according to them, not the dial.
  • Use more than one thermometer to measure the temperature of your aquarium. Don't rely on a single reading. Thermometers come in a range of styles and prices. There are even some models that will alert you when the temperature rises too high, like the Lifegard Aquatics Big Digital Temperature Alert or Tom Aquatics Aquarium Temp Alert.
Berlin Sump
Berlin Sump
  • If you already own a chiller or are considering purchasing one for the warmer months, you shoulder consider one with a dual-stage controller that allows you to control both your heater and chiller (this prevents them from both being on at the same time to conserve energy).
  • Have a backup heater ready to go, especially if you are only running a single heater on your system. It is a small investment to help protect your livestock!

Types of Heaters

Now that we have covered some aquarium heater best practices to help prevent disasters from occurring in your tank, let's now discuss the pros and cons of the most popular types of heaters available to aquarium hobbyists today.

Glass Tube Heaters

One of the most popular types of heaters we sell is the glass tube variety, such as the Eheim Jager TruTemp and the Hydor THEO. Both of these heaters are submersible, but there are other types of glass heaters that clamp on the rim of an aquarium (these are more often seen in freshwater systems). Glass tube heaters encase the heating element and thermostat inside the glass to protect the electronics from getting wet. These heaters can be made out of a variety of glass types including quartz, Pyrex and other break-resistant materials. Higher quality glass is always recommended to prevent possible cracking.

Glass heaters are usually among the least expensive compared to other types of heaters While many are made of shatterproof or shock-resistant glass, they can still crack or break
Wide variety of wattages available Cheaper brands may have inaccurate thermostats
Built in thermostat

Titanium Heaters

Titanium heaters are a popular choice for heating reef aquariums. ViaAqua, JBJ True Temp and Azoo Titanium heaters come with a controller and temperature probe to sense the aquarium's water temperature and energize (power) the titanium heating element to warm the water. Once it has reached the desired temperature, the controller will shut off the power going to the heating element.

Nearly indestructible Can be more expensive than glass heaters
Many include a digital controller The heating element can get quite hot and may even melt acrylic
The heating element is totally submersible Best used in sumps, not for use in a display tank
A variety of choices available in several wattages

Electronic Heaters

These types of heaters are relatively new to the marketplace but have the looks and features everyone is buzzing about. One of the most recent electronic heaters to be released is the Cobalt Aquatics Neo-Therm. We are hearing very favorable reviews from the reefing community since it debuted two months ago. Hagen also has an electronic heater, the feature-rich Fluval E-Series. Electronic heaters use an electronic thermostat that allows for a more accurate temperature setting.

Very accurate (usually within ±0.5° F) Higher cost than standard glass heaters
LED/LCD display for easy reading of temperature setting and water temperature There are not many options to choose from
Most have a relatively compact size

Inline Heaters

As the name implies, this type of heater is used "inline" with the water flowing from a sump return pump or canister filter back into the main tank. The return line tubing is spliced and the inline heater will be secured in place. The Hydor ETH 200 In-Line Heater is a perfect example of this style of heater (see diagram). Another example of an inline heater is the Lifegard Aquatics Heat Module, although this unit still requires you to insert a glass heater into the module (sold separately). Since these heaters are placed outside your aquarium, there is no risk of the heater being damaged by livestock or a collapsing aquascape. They are also an ideal choice if you want as little equipment in your tank as possible for a more natural look.

Hydor ETH 200 In-Line Heater
Hydor ETH 200 In-Line Heater
They don't take up space in a tank or sump You are limited by the tubing size they will fit
Most (like the Hydor ETH) have an automatic shut off in the event they run dry They can't be used in very high flow return lines
They must be used in a vertical position

Hopefully this article has provided you with some ideas of the preventive measures you can take to avoid heater-related issues in your own aquarium, whether it is a freshwater, saltwater or reef system. If you have questions, we'd love to hear from you! Please give us a call at 1-800-566-FISH (3774) or send an email to our tech support staff so we can lend a hand.

We would also like to hear about your experiences with aquarium heaters. We encourage you to leave a comment below to share what has worked for you and what has not. Have you encountered a heater disaster? Tell us about it!

Top 10 Heaters (October 2012)

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Approved Comments...
great infromation to know..and now, I will get a back up heater, i DO however wonder if there is something for loosing power to heat or keep my aquarium up to the correct temp. Thanks, Tonya Approved: 10/29/2012
Information is properly placed in categories of applicable types with pros/ cons listed. Lots of info to consider which most people would not know about. I am very aware of heaters going bad as I have had some heater disasters myself. One thing left out is to assure the heater is going through a GFI circuit. Approved: 10/22/2012
I lost my best tank of fish last fall. All info to assist decision making is really appreciated!! Approved: 10/19/2012
Article Details
Created on 10/17/2012.
Last Modified on 10/19/2012.
Last Modified by Dot Yuson.
Article has been viewed 16337 times.
Rated 9 out of 10 based on 22 votes.
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