Aquarium Heater Basics: Ideal Temperatures, Using Them, and More

fishes in an aquarium with aquarium heater

Aquariums are a great way to house beautiful fish of all kinds and colors. While they may seem simple, aquariums can be difficult to balance and get right. There are a variety of aquarium sizes, type of fish, and layouts you can choose for your aquarium.

One of the most important elements to consider with your aquarium is the water temperature. In order to regulate the temperature, you will need an aquarium heater.

Why Use an Aquarium Heater?

If you want to have fish that are both healthy and happy, then you need to have an aquarium heater. Fish, unlike mammals like us, are unable to produce their own body heat.

FREESEA 100Watt Aquarium Heater with LED Temperature Display for 10-20 Gallon Tank

Fish must rely on the temperature of the water around them to help regulate their body temperature. Due to this fact of fish biology, it is vital to ensure your aquarium is maintained at an adequate temperature.

Choosing the Right Aquarium Heater

Fish Aquarium

It’s important to understand the various types of aquarium heaters so that you can find the right option for your aquarium. Besides knowing what each is made to do, you will be able to determine what size of a heater will be right for your aquarium.

There are four main types of aquarium heaters you will come across.

  • Glass Tube heater
  • Titanium heaters
  • Electronic heaters
  • Inline heaters

Each type has unique qualities, and each has both pros and cons for using them to heat your aquarium.

Glass Tube Aquarium Heaters

Glass tube heaters are one of the most popular sellers. They come in both submersible forms and a type that clamps on the rim of the aquarium.  With these types of heaters, the heating element and thermostat are encased with a tube of glass to protect the electronics from getting wet.

Aquatop Aquarium Glass Submersible Heater, 300-Watt with Liquid Crystal Vertical Aquarium Thermometer

There are a variety of materials used in creating the glass tube, such as quartz, Pyrex and other break resistant materials. When possible, it’s recommended that you buy a thermostat that has higher quality glass in order to lessen the chances of it cracking.

Pros of this type of heater include that:

  • They’re one of the least expensive heaters on the market
  • They come in a variety of wattages
  • They have a built-in thermostat

Cons of this heater type are that cheaper brands may contain inaccurate thermostats, and while the glass tube is made of shatterproof material, it is still possible for them to crack or break.

Titanium Aquarium Heaters

Titanium heaters are another popular choice and can mostly be found in reef aquariums.

Finnex HMA-500S Electronic Controller Aquarium Heater/Titanium Tube/Heater Guard

A number of titanium heaters come with both controllers and temperature probes that are able to sense the aquarium’s water temperature. When needed, they can cause the heating element to warm up the water.

Once the desired temperature has been reached, the controller will shut off the power going to the heating element until it is needed again.

Pros of this type of heater are that:

  • They are nearly indestructible
  • They often come with a digital controller
  • The heating element is completely submersible
  • They have a variety of choices that are available in several wattages

Downsides to this type of heater are that they can be considerably more expensive than glass heaters, the heating element can get very hot and melt acrylic, and they best used in sumps and not in display tanks.

Electronic Aquarium Heaters

Electronic Heaters are fairly new to the market but have created a buzz because of their looks and features. These types of heaters utilize electronic thermostats to get a more accurate temperature reading.

Fluval Advance Electronic Aquarium Heater (300 Watt)

These are also great for those who use reefs in their aquariums.

Pros of this type of heater include:

  • A high accuracy, which normally falls within 0.5 degrees Fahrenheit, plus or minus
  • The LED/LCD display make reading the temperature easy
  • Electronic heaters tend to come in compact sizes

Cons of this product are they cost significantly more than traditional standard glass heaters. There also aren’t a lot of options out there yet, either, since these are fairly new to the market.

Inline Heaters

Inline heaters are a type of heater that uses water flowing from a return pump that is heading back into the main tank. The return line gets spliced with the inline heater.

150w/300w/500w In-Line External Heater AQUARIUM HEATER - 150/300/500 WATT 1/2'-5/8' (150 Watt 1/2'(12/16mm) Hose)

These heaters are designed to be outside of your aquarium and are great for avoiding damage that might be caused by falling rock or aggressive fish.

Also, if you are going for a natural look in your aquarium, then this is a great choice as none of the heater’s equipment is inside of the tank.

Pros of this heater are that they do not take up space in your aquarium and have an automatic shut off in case they ever run dry.

Negatives for inline heaters include that you are limited by what type of tubing size the heater can connect to. These heaters cannot be used with a return line that has a high volume of flow.

Another potential con is that these heaters have to be used in a vertical, upright position, which may limit your placement options.

Tips to Prevent Aquarium Heater Failure

Having your aquarium heater fail can be disastrous for your fish. The best-case situation is that the heater shuts down and the aquarium drops a few degrees. The worst case is the heaters can overheat or even crack open.

No matter how the failure presents, it can be potentially fatal for your fish.

Thankfully there are some measures you can take to help prevent catastrophic damage to your aquarium and fish.  

  • Do your homework before you purchase an aquarium heater. You need to find a heater that is the appropriate size and power for your aquarium, while also being a high-quality product. While you may pay more up front for the heater, it is better to buy a quality heater than have to replace your entire livestock a few months later due to a faulty heater.
  • After the initial set up, there is very little maintenance needed for an aquarium heater. On a regular basis, check to make sure it turns on and off properly, that there is no wear on the electrical cords, and that the heater itself is free of build-up.
  • When you set up a new aquarium, you should allow at least twenty-four hours for the water to adjust to temperature that is set on the heater.
  • To make sure you get the most precise temperature control with your aquarium heater, make sure to use a temperature controller. These are sometimes called a system controller.
  • Keep in mind that while most heaters do have built-in thermostats, this is the part of the heater which is most likely to fail first. If the built-in thermostat breaks, the heater cannot properly turn on or off, and can cause damage.
  • If you are using both a temperature controller and a heater with an analog dial thermostat, make sure to set the temperature a couple of degrees cooler than the heater’s thermostat. This serves as a back-up in case the controller fails to shut the heater off.
  • One trick is to use multiple heaters instead of just one. For example, if the tank needs 500 watts of heating, try using two 250-watt or three 200-watt heaters. This will help safeguard against heater failure, or help prevent one of the heaters from getting stuck on one position.
  • Make sure you place the heater where it is easy to access and check on. For example, don’t put it under a stack of rocks.
  • You should also place the heater where it has good water movement so that the heated water gets circulated throughout the entire tank.
  • If you are using a glass heater, make sure to take measures to protect it from falling rocks and larger aggressive or predatory fish.
  • If you use a titanium heater, make sure you do not put it against anything acrylic or it can melt – this includes acrylic tanks.
  • Between the dial on a thermostat or a thermometer, trust your tank’s thermometer. It is far too easy for a thermostat to break or be inaccurate.
  • Don’t be afraid to use more than one thermometer to measure the temperature, and never rely on just a single reading of the water temperature. Be sure to get a higher quality thermometer, as a cheap one can give severely inaccurate readings and cause harm to your fish.
  • If you are planning on using a chiller for the warmer months of the year, get one that has a dual-state controller. A product with this feature allows you to control both the coolness and heat of the tank.
  • If you are running on just a single heater, make sure you have a pre-purchased backup heater just in case something goes wrong.
  • List Element

Finding the Best Aquarium Heater

It is important to choose the right kind of aquarium heater so that your fish will be healthy and happy. That means they work accurately – read reviews from real users before purchasing. And it means that they will work properly in the aquarium environment you’re setting up.

Review the types of aquariums listed above, and then go research the top choices before you buy. Your fish are worth the investment of time.

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