Best 100 Watt Aquarium Heater for 20-30 Gallon Fish Tanks

Product TypeProduct NameCheck Price
Aqueon_Pro_HeaterAqueon Pro Heater 100W for 20-30 Gallon Fish TankCheck Price on Amazon
cobalt_aquatics_neo_therm_heaterCobalt Aquatics Neo-Therm Heater 100W for Tanks Up to 29 Gallon Check Price on Amazon
finnex_Aquarium_HeaterFinnex Electronic Heater Controller with Titanium Tube 100 Watt Check Price on Amazon
tetra_ht_submersible_aquarium_heaterTetra HT Submersible Aquarium HeaterCheck Price on Amazon
fluval_heater_100wFluval E Electronic Heater 100W for Tanks Up to 30 Gallon Check Price on Amazon
odyssea_aquarium_heaterOdyssea Aquarium Heater Submersible 100W Check Price on Amazon

Aqueon Pro Heater 100W for 20-30 Gallon Fish Tank


The Aqueon Pro heater has a durable built-in quality, having a non-corrosive shell for power & equal distribution of heat. The 100 watt aquarium heater is provided with thermostats for exact temperature settings & safety.


The LED indicators are present in the aqueon aquarium heater for the indication of a certain temperature when the indicator is red it means the heater is at high temperature & when the indicator is green it means the heater is working at normal temperature.

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This 100 watt aquarium heater can be used in freshwater as well as in saltwater fish tanks & can be positioned horizontally or vertically.

Product Reviews

This is one of the best aqueon 100 watt aquarium heaters on the market today. It’s made out of aluminum, not glass, so you don’t have to worry that it will shatter if you leave it plugged in when you do a water change or if you drop it.

It’s fully submersible and has a very sleek, all-black design. Unlike other heaters that only have an indicator light that shows when it’s heating, the indicator light on this heater shows red when it’s heating and green when it’s reached the set temperature so you will know that it’s plugged in.

This aquarium heater ran low by about 4 degrees Fahrenheit as indicated using a floating thermometer. However, it turned out that the thermometer was actually the one that was running low by 4 degrees by using a calibrated digital cooking thermometer.

So if you find that this runs low, check your thermometer as it’s the one that is most likely running low. Aqueon states that the internal thermometer has been calibrated twice during manufacture to ensure accuracy.

Included with the aqueon Pro heater are two black clips with suction cups that allow you to attach it to your aquarium. It’s very secure if you use both of them. Using only one allows for the heater to rotate so use both for secure attachment.

Quick Read Setup Unique Fish Tank Background

There was a problem; the plastic covering for the indicator light was not seated properly and allowed water to enter the heater.
This Aqueon Pro Heater is very accurate, works extremely well, and is simple to use. It’s more accurate than the floating thermometers in the tanks!

Cobalt Aquatics Neo-Therm Heater 100W for Tanks Up to 29 Gallon


Cobalt Aquatics Neo-Therm heater has a super flat design & is equipped with “one-touch control” which ha all the power to control the heater on the fingertip.

This 100-watt aquarium heater has an exact ±0.5 F thermostat with an advanced electronic system. The LED indicators are present in the heater for the indication of a certain temperature, which is the Set temp & Tank temp that has a temperature range from 66ºF to 96ºF.

Cobalt Aquatics Neo-Therm Heater has an integrated thermal protection circuitry that shuts down when the heater overheats making it completely durable, reliable & safe. This 100-watt cobalt heater is available for freshwater as well as for saltwater fish tanks.

Product Reviews

Cobalt aquatics neo-therm heater is great and so durable. The Neo-Therm 100 watt aquarium heater itself is quite and is pretty thin/flat/low profile. It plugs into a regular wall plug and attaches underwater to the inside of the tank with a suction cup.

You can hide it in the back behind some plants and a castle ornament and now you can’t even see it unless you’re looking for it. You can also move some of the decors out of the way for the photo- you can see its circle dial and the top of the heater unit on the right.

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The black box in the middle is the filter. The 100 watt aquarium heater unit is made of one piece and is kind of like heavy-duty black plastic. You can’t imagine this ever breaking as a glass heater could.

The thermostat can be set in 2-degree increments anywhere from 70-90 degrees. The 100 watt cobalt heater also has a Neo-Therm Heater on the same dial as the thermostat which tells you if the water temp is colder, hotter or the same temp you set it at.

There is a single button on the top used to change the temperature setting in even 2-degree increments. It keeps your betta tank at 78 degrees no problem. Cobalt aquarium heaters light up to tell you when it’s heating and what the current temp is.

You can check from another thermometer for the first few weeks to make sure this heater is functioning properly. It has a 3-year warranty and it’s great that the company stands behind its products for that long.

The push-button on top does work rather hard, and you had to press it multiple times to advance each temperature increment, but once dialed in it was all set. It detects your tank’s temperature exactly, and what you will really like about it is that if you have to unplug it for tank maintenance.

The power goes out, this thing remembers your settings and will resume at that temperature once power is returned. So far it has maintained a consistent temperature in the aquarium. The LED display is a handy feature.

Finnex Electronic Heater Controller with Titanium Tube 100 Watt

Here is the new Finnex Electronic heater controller which has a compact nature & equipped with titanium which maintains the water temperature under ±2 F making it completely durable, reliable & safe.

The titanium tubes are anti-corrosive in nature which makes it indestructible for both freshwaters as well as saltwater aquariums.

This 100 watt aquarium heater can easily be hanged inside the aquarium & also has an electronic control system. The Finnex  Electronic heater has indicators present for the indication when the heater is being functioned.

Product Reviews

As for this heater, it’s small enough to tuck away behind a tall plant, and it’s very consistent even with pretty drastic fluctuations in the room temperature, once you match the actual temperature of the water with the adjustable heater controller.

You will find that setting the controller a couple of degrees below where you want the tank to be working well. The tank is on the small size for what this heater can do, but that’s ok.

The only negative I have about this heater is that the suction cups that are supposed to hold it to the glass are pretty lame. The cable to the heater is quite short when the heating element turns on/off, the controls make a pretty loud click.

This can be a little annoying at night if you are trying to sleep next to it. The thermostat and the numbers on the dial loosely relate to each other. If you set the dial to 80 Degrees you will get about 68 in the tank before the thermostat trips and shuts it off.

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It has a couple of really nice features-the controller outside the tank and while “shatterproof” glass heaters are ok, for any substantial size turtle or larger fish a heater needs to be truly unbreakable.

This 100 watt aquarium heater is unbreakable no matter how much it’s clawed or kicked about it neither breaks. It does get very hot and for reptiles or amphibians and even some fish, it should be encased in a protective mesh/cage of some kind.

You can use the plastic mesh tubes from Magnum micron filters which happen to fit nicely.

Tetra HT Submersible Aquarium Heater


The Tetra HT submersible aquarium heater is provided with automatic thermostats that have heat output to adjust the temperature at 78 F. The LED indicators are present in the heater for the indication, when the indicator is red it means the heater is heating & when the indicator is green it means the heater is at the standby position.

The 100 watt aquarium heater has a glass design that can bear the heat in the aquarium without any problem. The Tetra Ht submersible has a protection circuitry that shuts down in case there is a short circuit in the heater, making it completely durable, reliable & safe


  • This 100 watt aquarium heater is compact, fits well in the 5-gallon tank, though it would be hard to hide
  • Heats the water, it keeps the water in the “safe zone” in case of water temperature
  • Automatically adjusts itself, no need to do it manually
  • The 10 watt aquarium heater is fully submersible
  • Warms water that makes fishes happier than before.


  • The heater kept the water at 78 degrees for the first day only, by the next morning it was around 74 and hasn’t gone much higher or lower than that.
  • You can’t actually control the temperature to make it accurate to 78 degrees temperature.
  • The thermometer is inside of the heater, which is directly heating the water around it, not completely solid in the science of this, but it seems like that would cause it to always heat just below where it should, assuming all of the water was the temperature that the water around the heater is.

This heater works well and has kept a steady tempo in the betta tank which is 2.5 gallons. Easy to install, easy to use & easy to clean.

The 100 watt aquarium heater never heated the tank over the specified temperature. It is sturdy and made of real glass which is nice because it cleans well, but bas rubber to protect it from smacking against things.

There is a light inside that shows you when it is on, which is much appreciated. Overall a good product & highly recommended for small water tanks users.

Fluval E Electronic Heater 100W for Tanks Up to 30 Gallon


The Fluval E series heater persistently monitors & displays the temperature assuring the safe lives of aquatic species inside the aquarium. Some of the features that the heaters consist are:-

  • During the normal operation, the temperature indicator will change the color if it varies from ±2 F or more from the set temperature.
  • The temperature set by the user is precise & does not fluctuate.
  • This heater has an advanced safety feature, coated with glass sleeve which in anti-shock resistance & prevents the fishes to come in contact with the core of the heater
  • The 100 Watt aquarium heater can be adjusted at various angles, in which way the user wants.

Product Reviews

Great heater and very precise. There are a few steps one must follow in order to get it working correctly:

  • The 100 Watt aquarium heater is to be mounted at an angle of 45 degrees, and with the bottom end pointing towards your filter intake. If you can also point your filter’s output to push water towards it, even better.
  •  Let it rest in your aquarium for about 20 mins, then plug it in and wait around a minute before setting any temperature, it automatically does a self-test and goes through some heating on and off to calibrate itself.
  •  Don’t expect it to heat your aquarium right away it’s a very gentle heater. Once it reaches the desired temp, it turns green and the temperature stays there, no variances, unlike other heaters.
  •  Since it’s a smart and very visual heater, it will tell you everything is going on, so don’t be surprised if it stays blue or red for a long time, little changes in temps, and it will let you know.
  • I hope the above points will give you the best experience on the heater. Otherwise, a great product to buy!

Odyssea Aquarium Heater Submersible 100W


This submersible aquarium heater is now an integral part of the aquariums as they keep the water at a constant temperature so that the aquatic species can live peacefully without any hustle.

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The Odyssea submersible aquarium heater has a temperature controller which prevents the temperature fluctuations. It can be used in both saltwater as well as in freshwater aquariums.

Product Reviews

If you set the heater on 78F, the tank will stay at 78F only. It looks like a well-built heater. Another great feature of the heater is the cord. It’s not like most other cheap heaters that only have the 3-foot cord.

This cord is long enough to have the heater deep in the tank and reach the plugin and still have the drip loop. If this heater lasts a couple of years at this price it’s well worth the money.

This 100 watt aquarium heater is equipped with an LED indicator which ensures you that the heater is working.


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