Product: Submersible Heater Series
Manufacturer: Penn Plax
Price: $13-(75 watts) $14-(200 watts)
Pros: Heater is inexpensive and does a very good job. Holds its temperature well and is very durable.
Cons: The inability to set a specific temperature is a great drawback to a submersible heater. Not that much cheaper than the best of class Ebo-Jager.


While the submersible heaters made by Penn Plax are not nearly as established as their hang-on the back type. These heaters also show the durability and accuracy that have made them a staple in the hobby for many years.

Accuracy (7)

The tank that I tested this heater in was a difficult task for it. I set-up a 10-gallon aquarium with a exterior power filter. I then dropped the water level, sealed the aquarium, and put a hot lamp over the tank. In such conditions, maintaining the water at an accurate and consistent temperature is difficult for a heater to do.

The heater I used kept the temperature well within reasonable levels, never once getting too hot or endangering the fish that were in the tank. It was able to due this for a long period of time. (1 yr+) However, it did not keep the temperature within 1° of where I initially set it to stay. Again this did not harm the fish, as the temperature never strayed more than 3°, but there are heaters that will be more consistently accurate than this heater was for me.

Ease of Use (6)

As most people do not like putting their hands in the tank every time they need to adjust their heaters, most of the submersible heaters available on the market today allow you to set the heaters to a specific temperature and then never think about setting it again. My complaint with those heaters has been their extreme in accuracy in some instances. However, they are certainly much simpler to set than this heater is. The requirement of putting your hands in the tank to adjust the heater makes it more difficult to set.

The heater is easy enough to attach to an aquarium wall. It uses two-suction cups, as do all the submersible heaters I've worked with, but it attaches both of the suction cups to a single plastic sheath that connects easily to the heater. (much like the Ebo-Jager set-up, but much easier to attach and detach) The arrangement makes it easy to replace the suction cups after they live out their typical 1-year lifetime.

Reliability (9)

This heater has fairly thick glass, about the same thickness as the thickest on the market today. It is very slender and compact, making it much less likely to be accidentally broken. I ran my heater for nearly two years, and it never malfunctioned or ceased to function. I did not experience any extreme of temperature that was dangerous to the wide variety fish I kept in the aquarium over that time.

Based on my experience, I believe this heater to be quite reliable with a likely lifetime of 3-5 years. Based on the other Penn-Plax models, I would assume that if the heater did malfunction, it would not bake all the fish in the aquarium.

Overall (7)

While the Penn Plax hang-on the back heaters are the top of their class, this one is not quite there. However, it is the cheapest submersible heater on the market, and there are quite a few submersible heaters that are more expensive than this one that do not work nearly as well. If you cannot afford an Ebo-Jager, this is probably your next best choice in the submersible heater realm.

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