HOW AQUARIUM HEATER WORKS – Best heaters in 2020 & why we need it

Thanks for sharing!

How to Choose the Right Aquarium Heater - Aquarium Co-Op

Aquarium Heater is a mandatory equipment for all aquariums, you therefore need to know in details how aquarium heater works, because no tropical fish should be in a fish tank without a heater.

We will discuss all you need to know about aquarium heaters – what it is; how it works; which one to buy; and tips to use them.


What is an aquarium heater?

An aquarium heater is a small and simple electrical equipment that heats the water in a fish tank.

Why do we need an aquarium heater?

Since most aquarium fish in the market are tropical, an aquarium heater becomes necessary for the majority of the home aquariums. Unless you live in a tropical area, you must get an aquarium heater for your fish. Otherwise, they will die eventually either directly to freeze to death, or from the weakened immune system.

Even if the fish do not die right away, it will become less active when the water temperature is too cold. Very uncomfortable for the fish, and less fun for the fish owner.

How does the aquarium heater work?

An aquarium heater converts electricity to heat. As water absorbs heat quickly, a heater heats the water around it. So to have a heater working, it must be in the water with good circulation. All aquarium heaters will turn itself off once they have reached the temperature of the setting. No need to worry if the water will overheat. If the water gets colder than the set temperature, the heater will automatically turn itself on.

Are Aquarium Heaters waterproof?

Most of the aquarium heaters in the market are fully submersible. It means they are fully waterproof. You can have them completely submerged in the fish tank without a problem. In fact, all of them have a “minimal water line”. If they do not submerge deep enough, the heater will damage itself once it gets too hot. For these full submersible heaters, you might as well position them entirely in the water.

However, there are a few heaters on the market not fully submersible. These heaters have a “max water line” on them. You might not want to keep the water above this line. It can cause an electrical leak. I would not recommend getting these heaters. Not worth the trouble and potential danger.

How to choose an Aquarium Heater?

1. Fully submersible
Yes, I have mentioned this before. Save yourself some trouble and potential harm by getting a full submersible aquarium heater instead of a half submersible heater.

2. Adjustable
Some aquarium heaters are adjustable when it comes to the temperature setting. Some others are non-adjustable. Adjustable heaters are more useful as you can set the temperature at where you want it to be. However, if you are on a budget, the nonadjustable heaters might be a good choice as they are cheaper.

3. Brands
I’d just go for one of the better-known brands. The following are some good examples.
EHEIM Jager heater,
Fluval Electrical Heater
Tetra Heater
Rena Smart Heater used to be on my list as well since I have had good experience with it. Go for it if you can still find them.

4. Wattage
All heaters should have the manufacturer rated wattage and recommended fish tank size on them. Choose the right wattage for your fish tank is essential. By following the manufacturer rated tank size, you can’t go wrong, but neither it is wrong by not following their advice.

The generally accepted rule is to have 2~5 watts for every gallon of water. You may not need that much wattage if you live in a fairly warm place. We will go over this later.

Due to the automated nature of the aquarium heater, we already know the heater won’t overheat the water. So getting a heater rated too high for your fish tank won’t be a problem as it will just turn itself off more quickly. It won’t cost you more electricity at all.

However, you can save money on the heater itself by getting a lower wattage heater. The higher wattage the heater is, the more expensive it is.

The heater’s useful lifespan can also be shorter if it turns itself on and off too frequently. A lower wattage heater has less problem with that since it has to be turned on for a more extended period to sustain the same water temperature.

5. The room temperature matters when it comes to choosing an aquarium heater.
The one thing you might need to pay attention to is if the wattage is way too low. Generally speaking, the manufacturer rated recommended fish tank size is not very accurate. For example, according to most manufacturers, a 50w heater is only good for a 10-gallon fish tank.

I have personally used a 50w aquarium heater for a 40-gallon fish tank no problem. The water temperature can be anywhere I want it to be. I have set it at 80F, and it could go to 90F when I needed it to be.

However, there is one crucial factor comes into the play. It is your room temperature. My 40-gallon fish tank always sat in a room where the temperature had never gone below 73F or 22C.

When I moved to a different house, a 50w heater had trouble to keep the water temperature at even 70C in the water. When the room temperature went to below 50F (10C), the water temperature in the fish tank went down to below 70F even as the setting on it had kept it at 80F a month earlier.

So it is important to know the room temperature all year around. If it is a cold room, you might want to get a higher wattage heater to make sure it can heat the water to your target temperature.


1. Marina Submersible Heater 25 Watt

The Marina Submersible heater is made from impact resistant glass and has a waterproof seal. It uses suction cups for installation and they appear to provide a secure hold on the tank surface.

A bumper guard is provided that adds a layer of security between the heating element and your fish.

The temperature adjustment dial is easy to access and use, but it does not indicate specific temperature degrees which will require you to monitor the water temperature independently. HOW AQUARIUM HEATER WORKS

While this heater is more compact than many others, it is actually seven and a half inches in length, not the six inches advertised.

The lower wattage may prove beneficial to you with a tank that is five gallons or less.

2. Cobalt Aquatics Neo-Therm Heater, 25 watt

This 25 watt heater offered by Cobalt Aquatics is designed with a shatterproof outer casing that should provide you with a unit that is durable. The modern design is very thin, which is a great feature when used with a smaller tank.

The Neo-Therm is able to supply a temperature range from 66 to 96 degrees Fahrenheit.

A one-touch control system allows you to make adjustments more easily than other heater designs. Thermal protection circuitry adds a nice safety feature that can shut down the heater before it overheats. HOW AQUARIUM HEATER WORKS

You may find this compact unit working overtime with tanks that approach or exceed ten-gallons in water volume.

The LED display offers the temperature setting as well as water temperature readings.

3. FREESEA Submersible Aquarium Heater


This submersible heater is a space-saver designed for warming the water in tiny aquariums. It features a LED temperature display and it’s available in different power sizes (50-300Watts). Also, it is one of the Best Heater For Small Fish Tanks

The Freesea Aquarium heater must be submerged in water (heating rods must stay under water) and should not be left to run dry. When cleaning the tank or when changing the water, you should unplug the heater to prevent it from overheating.

You can set the desired temperature 59°F~94°F(15°C~34°C). The system’s automatic constant temperature function acts as a built-in thermostat turning off the heater when the desired temperature is reached and turns the heater back on if the temperature drops below the predefined value. HOW AQUARIUM HEATER WORKS

The LED display is illuminated for greater visibility, allowing you to monitor its operation more easily. The heater comes with a 12-month warranty.

4. Aqueon Flat Submersible Heater


Another small heater to consider for your tiny aquarium, the Aqueon Flat, is a submersible heater with a flat design that’s available in two sizes for aquariums up to 10 gallons.

The heater is fully submersible, shatterproof and it can be installed vertically or horizontally with the suction cups that are included in the heater kit. It’s ideal for glass or acrylic Desktop-style fish tanks.

If you’re keeping small tropical fish in an aquarium that’s under 10 gallons, this submersible heater can be the space-saving solution to heat your tank.

Like with many submersible aquarium heaters, this too should not be left to run dry. Always turn it off when cleaning the aquarium or performing water changes. HOW AQUARIUM HEATER WORKS

Now this may not be a fancy piece of equipment (no LED display or indicator), but it’s also extremely affordable.

5. Hygger Submersible Quartz Glass Aquarium Heater

Hygger’s heater is a mid-ranged sized submersible unit. Is built with quartz glass that should prove adequate for light handling. The product comes with a protective sleeve designed to protect the glass as well as your fish.

This heater can be adjusted to temperature settings between 61 and 89 degrees Fahrenheit.

The temperature is adjusted with a turn knob located on the top of the unit and is easy to turn, which is a bonus feature for those who may struggle with turning some controls. The unit may register slightly off with larger volumes of water, but it does provide a consistent level once set. HOW AQUARIUM HEATER WORKS

The quartz glass element shield may prove brittle if not handled with care.

The fresh and saltwater design should help to prevent corrosion over time.

6. Hydor Submersible Glass Aquarium Heater

The Hydor glass heater uses PTC design technology which can offer you a glass heater that is resistant to shocks and is more durable than other glass submersible heater designs.

The scale on the adjustable controls is graduated in a scale of two degrees, allowing you the ability to adjust temperatures with a minimal amount of effort.

The Hydor will not be damaged if ran dry on accident.

The Hydor is equipped with a cord that is approximately 73-inches in length, which offers more set-up possibilities than some of the other products in this wattage.

This heater would benefit from a reduction in the current length of 10-inches, also it is one of the Best Heater For Small Fish Tanks

This heater offers a stable temperature, supplying the tank with even heating throughout the water column.


Thanks for sharing!
Click Here to Leave a Comment Below 0 comments

Leave a Reply: