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Heater Impressions

Heater Impressions

By Steven Pro

Most aquarium fish encountered at the local fish store are tropical in origin (Don’t get the term "tropical" confused with "marine".  "Tropical" refers to the temperature of the water that a fish hails from, not its salt content.).  Since they require warm water, the aquarium will require a heater of some sort.  While heaters generally come in two forms, hang-on and submersible, I almost always sell and use submersible heaters.  I find them to be of higher quality than the hang-on models.  Submersible models are more expensive, but the added cost is minor relative to the overall aquarium setup, and the greater safety makes them well worth it.  I have seen a dozen or so instances of heater failure, and in every single instance the heater has stuck in the "on" position.  I have yet to see a heater break and simply fail to operate.  For some reason, when they go they try to take the entire tank with them.  Because of this, I try to seek out the most reliable brands and stick with them.

Although most fish are tropical, there are some notable exceptions to this rule.  Goldfish and Koi are the two most commonly seen cooler freshwater fish seen at most pet shops.  Some cool water marine fish are also occasionally offered for sale, including Catalina Gobies and Leopard Sharks. These fish are definitely not tropical and do best in cool water, generally no higher than 72ºF, with 60’s being even better.  Even though systems for these fish may not require a heater, they are unusual exceptions to the tropical rule.

There are also some marine setups that utilize high intensity lighting that produce so much heat that a heater is not necessary and in some cases, a chiller (water cooling unit) is needed.  But, even in those instances it is not a bad idea to also incorporate a heater into the system as a backup.  In the case of a reef display with lighting bearing the burden of heating the water, what if a light bulb was to burn out?  If this were to happen and there was no heater backup, what would have been a minor annoyance until a new lamp was obtained could become a total catastrophe as the water temperature began to drop to the relatively frigid room temperature. 

Here is a roundup of some the more commonly encountered brands of submersible heaters:

The Visi-Therm Deluxe. Note the bright red setting indicator and full range temperature scale.

Aquarium Systems Visi-Therm

This was my preferred heater for quite some time.  I have probably installed hundreds of these in my career and have only had a few go bad in over ten years of working in this industry.  They had a full temperature range from a low of 65º to a high of 89º and they were completely adjustable to anywhere within that range.  Unfortunately, since Aquarium Systems and Marineland became part of one larger company,  the original Visi-Therms are no longer being made and have been replaced by the Marineland Labs/Aquarium Systems Visi-Therm Deluxe and Visi-Therm Stealth heaters which I will discuss later in this article.

Aquarium Systems Eco-Therm

This was Aquarium Systems venture into a base model line of heaters.  They were ostensibly the same as the Visi-Therm, but they did not come with the numbered scale.  They only had a light to show when the heater was on and a knob for adjustment.  You had to use a separate thermometer to read the water temperature and then adjust the heater appropriately.  This really never bothered me because I always have a thermometer on a system to monitor the water temperature independently of the heater.  As such, these were a great buy, inexpensive and reliable.  Even better,  they were occasionally included for free in buckets of Aquarium Systems Instant Ocean or Reef Crystals salt mix.  This was perfect to use for heating freshly made saltwater in a mixing vat to match the tank’s temperature.


At one time, these were the gold standard of the aquarium industry but I don’t like the newer designs.  For one, they are no longer completely submersible.  They have added a line on the top of the heater unit and labeled it, “Do Not Submerse Beyond This Point.”  I have heard on some of the internet message boards that this was done only for the UL listing and the heaters are still safe to submerse, but I don’t feel comfortable doing so in clear violation of the labeling.  From a business/liability standpoint, it is not safe for me to do or recommend to others.  So, until such time as the labeling is changed, I will not be using these units submerged.

Also, about two years ago I ordered in a case of twelve 250 watt units.  Of those twelve, two were defective right out of the box.  It may have been a fluke and I just got a bad shipment, but that was the last time I bought any Ebo-Jager heaters.

Marineland Dual Temperature

I only used a few of these heaters shortly after the supply of Visi-Therms dried up and I immediately didn't like them.  They only have an adjustment for two temperatures, 76º or 82º F.  I prefer to keep my marine aquariums somewhere in between 78º and 80º degrees.  In my opinion, 76 is too cool and 82º too hot.  I ended up using them on freshwater community tanks set for 76ºF because that is a reasonable setting in my opinion.  In that capacity, they are served me well, but they don’t give me the fine tuning control that I would like to have for all my customers’ tanks. 

Tetra/Second Nature Acura

Tetra Acura heaters come in a range of sizes and have performed reliably.

This is one of the only brands of heater that I have never experienced a problem with, but that seemingly ringing endorsement comes with the caveat that it is also one of the brands I have used the least.  So, take that statement for what it is worth.  As I said when I began, I have used Aquarium Systems Visi-Therms for most of my career and time in the hobby.  Once those disappeared, I changed to Ebo-Jager, then Marineland, and finally these Tetra heaters.  I have not had any complaints about these in the short period of time that I have been using them, and they do seem to be reasonably well built and come with the features that I desire. 

Summary & Future Heaters of Interest

In all likelihood, I will be switching heater brands yet again.  Not that I have been unhappy with the Acura line.  They have served me and my customers well for the last year or so.  It is just that Marineland has just resurrected the Visi-Therm moniker with the Visi-Therm Deluxe heaters.  These seem to be the old Aquarium Systems Visi-Therm line with a few minor changes.  The biggest of which is the lifetime guarantee.  Between that and my previous exceptional experience with this brand, I am going to switch back as soon as my supply of Acura units is gone.

Heater Hints

Handle with care!  Carrying or hanging heaters by the cord and general rough handling can break glass, damage seals or damage thermostats.  Also beware that heaters can't be dislodged or damaged by livestock, especially when using suction cups.

Beware of thermal shock!  Heaters will overheat and break if removed from the water while plugged in.  Having a dedicated heater compartment in a sump or placing heaters low in the tank will prevent them from being exposed during water changes and maintenance.

Add a controller! Inexpensive dedicated heater controllers are becoming more widely available and are cheap insurance against heaters that "stick on".

Two small heaters is better than one big one!  Using two heaters that are each rated for half of the tank size makes it hard for one stuck heater to overheat the tank, but also prevents a severe drop if one fails to come on at all.

Clean and inspect often! Keeping heaters clean ensures that the settings and indicator light will always be visible.  It will also allow problems like condensation, corrosion or a "stuck on" condition inside the heater to be caught early.

Don't get shocked!  GFI outlets (like in your kitchen or bathroom) are always a good idea when electricity and water come together.

I have also been intrigued by the recently released Aquarium Systems Stealth heaters.  They have replaced the glass in most submersible heaters with a non-breakable composite material.  This seems like a great idea.  In addition, these heaters are also supposed to have a special sensor in them that automatically turns off the heater when exposed to air, which is another nice new feature.  Unfortunately, my preliminary inquires of others that have used this new line has been mixed at best  Some people have complained on the various internet message boards that these heaters are having problems maintaining the target temperature.  While I was initially interested in these units, I don’t think I will be trying these out just yet.

You may have also noticed I have not commented on any of the newer titanium heaters that have come out in the last couple of years.  That is simply because I have not used any yet, although I am very intrigued by them.  You may also have noticed from some of my other columns that I am not one to jump on the latest trend.  I usually sit back, wait, and watch how the newest piece of technology or methodology works for others before I invest my own money in it.  It is this mentality that has stopped me from investigating these units further.  Along with my normal conservative approach toward unproven technologies is the fact that many of the companies that are currently offering titanium heaters are relative newcomers to the industry.  I had not even heard of them a few years ago, so I am even more wary about trying these units out, given the fact that a heater malfunction is one of the easiest ways to wipe out an aquarium!  If a company the caliber of Eheim or Tunze released a titanium heater, I would be very willing to try it, but  until that time, I am sticking with the glass models that are widely available and keeping my fingers crossed.

Heaters and Heating on WWM

Related FAQs: Heating Marine Systems, Heating 2, Heating 3, Chilling 1, Chilling 2, Water TemperatureHeating Freshwater Aquariums,

Related Articles: Marine System Components, Coldwater SystemsControllers



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