Best External Aquarium Heater (Reviews)


Fish tank water heater is probably the most important equipment in your aquarium. Water heaters which are reliable, safe for your aquarium creatures. Also high-quality can create a comfortable environment for your fish tank inhabitants in any season. It is highly important to keep certain aquarium temperature because some fishes and plants species needs higher or lower aquarium water temperature than the regular room temperature. It does not matter if you have large or small fish tank. You still need the best  aquarium heater to ensure your fish tank inhabitants well-being.

There are two main types of aquarium heaters: external and internal aquarium heater. If you have an aquarium and dream about having aesthetic view without heater or filter hanging oddly in the fish tank we recommend you to consider buying external aquarium heater which will be practically invisible.

So in this article we will help you to choose the best external aquarium heater for your fish tank.

external aquarium heater
Hydor In-Line Aquarium Heater

ETH Heaters are the first external heaters for aquariums with the exclusive PTC technology. The self-limiting PTC heating element guarantees maximum safety against any risk of overheating. Designed to be used on return lines coming from canister filters or sumps.


  • Suitable for both marine and freshwater aquariums.
  • Two power options ( 200w and 300w).
  • High precision electronic temperature control.
  • Easy to use for beginners.
  • Two hose options (5/8″ and1/2″).
  • Silent operation.
  • Great quality.


  • Pricier than other competitors.

ista aquarium heater
ISTA In-Line Aquarium Heater

The ISTA in-line external heater is designed for vertical use in most aquarium applications involving water hose of the specified diameter. This external aquarium heater is easily installed by cutting the tubing and connecting the two parts of the tube to each side of external heater.


  • Termal spraying glass (speed up heating process).
  • Auto power off safety system (when temperature is over 96.8°F and when temperature is 37.4°F more than setting temperature).
  • Three power options ( 150w, 300w and 500w).
  • Two hose options (5/8″ and 1/2″).
  • Suitable for both marine and freshwater aquariums.
  • Two sensors to exam the temperatures of water inlet and outlet.


  • Might be difficult to install, but you can find plenty of information available on the internet.

poity aquarium heater
Poity Fish Tank Water Heater

Cheaper than other competitors listed above. Still has good quality and guarantees more comfortable life for your fish tank inhabitants. This option will suits those who are more on the budget side.


  • Suitable for both marine and freshwater aquarium.
  • Silent product.
  • Anti crash, anti brake and corrosion resistance.
  • Two power options (300w and 500w).


  • Made from plastic.
  • Weaker when it comes to quality comparing to other competitors.

In conclusion,

Taking everything into consideration, external aquarium heater will definitely suit those who wants aesthetic, nice fish tank view. When there are so many products available on the market be careful and choose the best one for your lovely fish tank!