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Aquarium Heaters; Review, Size, Heater Information
By Carl Strohmeyer
- Heater Overview
- Set Up Suggestions
- Types of Aquarium Heaters
Aquarium Heaters have come a long way since I first named this article, as many years back there were just the automatic (non pre-set) hang on the back heaters or the submersible glass pre-set (thermostatic) heaters.
Now even in the glass/quartz submersible heaters, they can vary greatly in size and accuracy of the pre-set and variances of 3 degrees Fahrenheit in either direction.
We now have Titanium Heaters, Digital Heaters (that not only are more accurate than their analog counter parts, but most of the Digital Heaters are available with “auto over-heat & run dry safety shut offs”.
Another popular newer heater type is the under-gravel or “Mini” heater that has no temperature controls at all, and are simply meant to raise the ambient temperature in a Betta bowl or similar.
As for heating requirements, I recommend 25 watts of heater for every 10 degrees of ambient temperature per 10 gallons you need to raise your aquarium temperature.
EXAMPLE: If your home is 68 degrees and you have a 40 gallon aquarium, to reach a temperature of 78 degrees you would need a 100 watt heater.
Often when heater problems occur it is due to the heater being of the improper wattage to meet heating requirements of an aquarium in the location it occupies. Too high a wattage can result in rapid temperature rises that can result in cooked fish if you make adjustment mistakes.
The above formula is a VERY accurate guide and I have used this formula for many years with no issues of under or over heating. In fact I have often witnessed less than honest retailers tell a customer that (for example) they need two 300 watt heaters for their 125 gallon aquarium when in reality ONLY ONE is required for the average room that is kept at 68 degrees during the cooler hours (usually at night while asleep).
So PLEASE be careful with stores or web sites that try and over sell you as to your heater needs.
Also, if your room is warm (such as in summer months) you may end up with aquarium temperatures higher than your settings (example: a room that is 85 will keep an aquarium at 85 even if your heater is set at 78 F).
It is important of all heaters, regardless of type to maintain good circulation around the heater for the best results for temperature control and accuracy. I have used (& even designed my own) heater modules for in-line heater applications and I will be the first to admit these do not properly dissipate the heat, especially with titanium heaters.
Even though I really like the durability of Titanium Heaters, these types of submersible aquarium heater are best used inside the main display aquarium where the heat will dissipate more rapidly than in a sump or similar enclosed space. I have witnessed Titanium Heaters (of different brands) over heat and burn out when used in small sumps or heater modules. I recommend using a glass or quartz submersible heater in sumps or similar as glass submersible heaters do not seem to be as sensitive to this problem.
Another point is often when the ambient temperature is more than 25° F (14° C) under the desired temperature, the use of two appropriately sized* heaters often works better from my experience.
*By appropriately sized, I mean using the above cited formula.
As well, on the "top end", aquarium heaters are designed only for a top temperature of 90° to 95°F (32° to 35°C), so attempting to heat any higher will likely result in failure and even damage to the to heater.
SET UP SUGGESTIONS
- When ANY heater is to be initially used, you should place the heater in the aquarium for 20-30 minutes prior to plugging it in so as to allow the temperatures to equalize internally.
With low end Automatic Hang on the Back heaters make sure that the water is up to the water line, if too high or low this can cause heater failure or malfunction.
With pre-set submersible you need to make sure that the heater is submersed at least to the minimum water line.
Since Automatic Heaters generally do not have temperature pre sets, all inputs of temperature control on the dial should be made in increments of not more than ¼ turn, with 1/8 turn being better.
- With Pre-sets and digital heater controls, I recommend to not change temperature more than 4-5 degrees F per day if fish are present (this does not matter if there are no fish or other “creatures” present).
Also make note that temperature pre-sets are just a guide and that it is quite common to set a heater at 75 F and have the actual temperature be plus or minus 3 degrees F.
- If two heaters of more than enough "Wattage" are employed in a tank, I suggest adjusting each one individually over a few days time prior to running the heaters together.
An example would be two 200 Watt Heaters in a 100 gallon aquarium.
I have found that when two heaters are used for whatever reason (although usually for redundancy), it is easier to "set" correctly with one heater running at a time.
However if two heaters are used that require the combined wattage for properly heating an aquarium based on ambient temperature; both would need to be set at the same time, which often results in a bit of heater "ping pong" since even the best heaters are often off in their settings by a degree or two.
- Make sure a "drip loop" is employed with any heater installation so that the power cord coming from the aquarium or sump does go straight to the electrical socket; rather a loop (a 'U' in the power cord) is utilized that allows any water that can possibly follow the cord from entering the wall socket and starting a fire.
Many manufacturers of heaters will discourage the use of power strips for "Legal" reasons, however these can be safely used if properly attached to the aquarium stand or wall so that ALL power cords have a drip loop prior to plugging into the power strip.
Be careful with the use of extension cords as these can more easily allow water following the cord to enter the socket.
As well any coiled extension can allow over heating of insulation allowing for the possibility of a fire, so make sure to keep any extension cords from being coiled.
My suggestion, if an extension must be used, is to use a singe outlet 14 gauge or lower, heavy duty electrical extension cord. Make sure it is NO LONGER than needed (no unnecessary length), as well, I suggest a small bead of silicone around where both power cords connect to prevent moisture for getting in (since silicone does not adhere that well to the material used for power cords, the silicone forms an excellent gasket that is also easily removed when the need to disconnect arises).
- After you set up a glass or quartz aquarium heater, it is quite common to see condensation moisture inside the heater tube.
This is not a concern for alarm unless liquid is actually accumulating inside the heater tube.
I have witnessed this many times over the 4 decades I have kept aquariums professionally and sometimes it goes away and sometimes these few droplets of moisture seem to always be present when the heater is on. What I also know for sure is I have never had this shorten the life of any heater (out of 1000s used with my many clients aquarium).
PRESET HEATERS; Thermostatic (Analog) Submersible Glass or Quartz Heaters:
The Thermostatic or Preset Heater has a built in analog thermostat (or a remote sensor, as is common in many titanium aquarium heaters).
These heaters may use a thermostat, usually monitoring the impedance of a thermistor (a resistor used to measure temperature changes in the aquarium, relying on the change in its resistance with changing temperatures), OR the potential across a thermocouple (a temperature sensor used to measure electric potential difference).
As noted at earlier, most Pre-Set Submersible Glass Heaters have some variances, however that said the biggest difference between different brands is not this variance, but in quality of durability, price, and even manufacture return policies.
I have used MANY different heaters over the years in my service business (the numbers are literally in the 1000s) and what often happens is the heater either ceases to work or the variance becomes greater. As well, many of the name brand Heaters are often no better with this than others.
An example would be the excellent Hagen Tronic Heater, which is an excellent and durable heater, but it is more costly than the Via Aqua, SunSun or other lesser known brands of often equal or even better quality.
Another problem I have found is that some excellent heaters such as the Ebo Jager have difficult return policies whereby I could not accept a customer return directly to me, rather I had to send these directly to their manufacturer all the while the customer was without their heater. This is the reason I ceased recommending these heaters for my clients (not because of frequent quality issues; but lets face it, even the best heater fails occasionally).
Recommended Quality Heater Product Resource:
There are many models of aquarium heaters available today that are available preset or with a temperature gauge on the side of the heater or on the control knob to help the aquarist set the temperature, most all of these heaters are completely submersible as well.
These Submersible Thermostatic Heaters should be kept under water or NO higher above water than the minimum water line mark that most of these heater have, generally about 2-4 cm below the top of the heater. There is some confusion that these heaters cannot be submerged totally, however I have never used or found a brand of Pre-set thermostatic glass/quartz submersible heater that this is a problem.
The aquarist should allow the heater to adjust to water temperature for 30 minutes before plugging in this type of heater to allow the thermostat to adjust. Use these settings on the dial as a guide to make fine adjustments, as they should NOT be depended upon for total accuracy.
Though some manufacturers make other claims, these gauges are at best accurate within two or three degrees Fahrenheit (one to one and a half degrees Celsius), and generally get less accurate over the life of the heater.
An aquarist should ALWAYS CHECK their heater for accuracy and not assume that because it is set at 78 F, it will stay at 78 F.
It is not un-common for even the best of these heaters to be off from their “pre-settings” by a few degrees. So for instance if your pre-setting takes a setting of 76 F to maintain 78 F (& 78 is what you desire), you should use the setting of 76 F.
I also recommend turning off all heaters when water is to be changed that would exposed any part of the heater sensors or heating elements (which is usually most water changes). I recommend waiting at about 10 – 15 minutes for water and heater temperatures to equalize before re-starting a heater after a water change
For Further Reference:
Aquarium Cleaning; Basic Steps
Submersible Heater Brand Suggestions:
I have been asked this question many times, so I will include my observations of common submersible heater brands.
Please note that while this is obviously subjective; with the many brands I have literally used and dozens if not 100s of each brand, I have had a reasonable amount of experience in this subject.
All three of these suggested heaters have accuracy that are more than good enough for most aquarium applications (+/- 1-2 F). In fact, the accuracy with these (and likely some others not listed here) is very close to many heater including Titanium that cost considerably more.
These suggestions are based on my professional use in my aquarium maintenance business going back to 1978 and literally 1000s of aquariums.
A final note is I am only naming those I have had a good experience with, NOT the bad ones!
*Ebo Jager (Eheim); Excellent and very reliable heater. One of the best if not the best.
The only negatives are price and a poor return policy when the rare defective heater does occur that requires the owner to ship directly back to Eheim/Ebo Jager while the aquarium keeper is without a heater for several weeks.
There were some quality issues when manufacturing changed, but this has been corrected according my friends active in the aquarium maintenance industry.
*Via Aqua & SunSun; While not as well known in some parts of North America, this heater IS well known & popular in the Western USA.
This heater is among the best in reliability (the Ebo Jager is likely the only more reliable heater), yet is one of the more affordable with a more gracious return policy when a defective heater does occur.
Product Resource Link:
Via Aqua Submersible Quartz Aquarium Heaters
*Hagen Fluval Tronic Submersible Heater: While I am not a fan of Hagen (in part due to their business practices), I have to admit this heater is darn good.
It is a reliable heater, albeit a little pricey compared to the Via Aqua, but just as reliable and quite accurate.
Generally most manufacturers of quartz/glass and titanium submersible heaters will state in their directions that the heater should be mounted in the aquarium vertically for the reason to keep water from compromising the seal at the top, this is really only a corporate liability statement as most well made glass submersible heaters such as the Via Aqua Glass/Quartz Heaters will be perfectly fine angled to fit in short aquariums or outdoor patio ponds.
I have mounted many submersible heaters for years in a sideways/horizontal mount without a compromise in the seal. This does NOT count for HOB economy automatic heaters which MUST be mounted on the back of the tank vertically.
However I do recommend a vertical aquarium mount whenever possible.
This is more of a sub-type of the glass submersible heater, however the manufactures of the these Digital Aquarium Heaters throw in more extensive digital control circuitry.
A few of the advantages over most glass submersible analog heaters (of which the vast majority of submersible aquarium heaters fall into this category) include:
*Run Dry Safety Shut-Off
*Double insulated heating element
*More accurate temperature control (variances under +- 1.0 F).
*Easy to read display the also displays aquarium temperature (via probe attached to this heater)
*HOWEVER from our use (& our "sister" aquarium maintenance companies), these heaters circuitry (such as the AquaTop) have failed at a much higher rate than the 3% or less that is considered "Good" for electronics.
So my current advice is to AVOID these heaters.
RESIN/PLASTIC COVERED HEATER
A Sub type of the Glass Submersible Pre-Set Heater the plastic resin covered aquarium heater. The Rena “Smart” Heater is a good example of this heater type. It has a low temperature variance with an LED warning alert system that flashes when water is +/- 5º F from set point. As well the SmartHeater works in any position, horizontal or vertical.
Another is the Stealth (by Marineland). This unique submersible glass heater has a hard plastic “Shell” which protects the heater from breakage.
However, please note that my experience with the Marineland Stealth Heaters indicate that they should also not be used in confined spaces or low water volume applications. I have also noticed (in part from feedback from others in the professional aquarium maintenance business) that the Marineland Stealth heater is not as accurate or as durable (generally in low flow applications) as the higher end Via Aqua Titanium Heater or the very high end Pro-Heat II Titanium IC Heaters.
My experience with the other Marineland submersible heater; the “Visitherm” has been worse with LOW accuracy/durability in varied conditions, at least the Stealth is accurate and reasonably reliable in higher flow aquarium placement applications.
TITANIUM/ STAINLESS STEEL/ REMOTE SENSOR HEATERS
Titanium and Remote Sensor Heaters such as the Via Aqua Titanium heater, both the earlier generation anaolog and next generation digital Titanium.
The advantage to these heaters is three fold;
One is that they tend to be even more accurate by having the sensor far from the heating element.
Two, besides improved accuracy of a remote sensor, the accuracy is further improved by the Digital electronics of the newest generation Titanium Heaters.
Three; the Titanium (and also Stainless Steel) heaters are much more durable and difficult to break especially with large fish such as Oscars.
These heaters also resist breakage due to aquarist mistakes such as leaving them on during water changes or dropping rocks on them (although Titanium heaters still can be damaged by leaving them on during a water change).
I think Titanium Heaters are your best choice for very large aquariums and for aquariums with large and destructive fish such as Arowanas, Oscars or even Turtle tanks (provided there is adequate water volume).
Also if accuracy of temperature control coupled with durability is important, especially with marine aquariums or Discus aquariums, the Digital Titanium is for you.
Titanium Heaters are NOT as good a choice for placing in confined spaces such as sumps, low water tanks (such as Viviariums) or filters such as the ReSun Internal Wet Dry Filter as Titanium heaters tend to easily overheat in confined spaces.
In the case of a sump, the reasons for spending extra for a Titanium heater which are impact resistance and the remote sensor are lost in this small space where the remote sensor is of little advantage and as well no fish are present that might damage a more fragile glass or quartz heater.
*Via Aqua Next Generation Digital Titanium Heaters
*ReSun Biological Internal Wet/Dry Filter
IN-LINE AQUARIUM HEATERS (or In-Filter Heaters)
The inline aquarium heater has come in and out of popularity in a few variations since at least the 1970s.
One form was the "heater module" in which to place your standard submersible heater inside of this "module". An example is the Lifeguard Heater Module which is the one I used the most; in fact I even designed one many years back to sell and utilize in my aquarium maintenance business.
Of late many other DIY versions have shown up on popular YouTube DIY channels
Another variation is the specific in-line aquarium heater such as the Hydor ETH pictured here to the left.
The third method (more similar to the first) is the use of canister aquarium filters with specific ports in which to place your heater.
This all said, all these methods have one thing in common from considerable use/experience on my part (as well as others who have been in the industry/hobby for some time), and that is these inline heaters often are NOT that accurate and more importantly cause heaters to fail at a much higher rate that more conventional aquarium heating methods.
This is why I stopped selling and making my own heater module as the failure rates and poor heating results were no better with my "invention" than others no matter how much I "tweaked it".
Part of the reason is the confined space does not allow for accurate temperature reading from the heaters sensors. As well this confined space often results in too much heat inside this unit that contains the actual heater/heating element, resulting in overheats and premature heater failure.
The bottom line is although on the surface this may seem like a good idea, in practicality it is a flawed idea that has been doomed to failure in every design I have tried or designed.
Unfortunately as with many already proven failed ideas, this one has once again been resurrected by a popular DIY YouTube channel. I think the problem is we have too many persons coming up with great ideas without any real practical experience, nor any research or willingness to learn from others who have much more practical experience (mentoring IMO is something I allowed myself to do in my early years, but seems to be a lost art from what I have seen and attacks made online).
If you desire this method due to large and destructive fish, consider a Titanium Heater.
If your reason is less equipment in the aquarium, consider placing your heater in a large sump system with much better circulation around the heater.
Of course this option is not possible to the majority of readers, so my suggestion is to simply hide your heater with decor, make sure to have a drip loop for safety, and simply realize that this minor inconvenience of a heater inside your aquarium is better than a failed heater or over heat of your aquarium.
One final issue with in-line heaters if used with an in-line UV Sterilizer, do NOT use together or at the very least use after the UV Sterilizer.
The reason? These heaters are notorious for having hot spots in the water just after the heater than can over heat a UV lamp and considerably shorten life, especially in low flow applications.
AUTOMATIC OR NON-PRESET HEATERS (Hang on the Back Heaters)
The Non-Preset or Automatic heater such as the basic Radiant Heater has a very remedial thermostat; or better they have metal contacts that are tightened by turning the dial (metal contacts installed on bi-metal lead, which are brought together with an adjusting screw).
When the heater is "turned up" or tightened, it turns on for longer periods of time. In other words these heaters are “automatic” not thermostatic as they do not go on based on water temperatures, rather the “time” it takes for a contact to “break” due to the tightness of the adjustment.
These heaters need adjustments between summer and winter.
Examples of this heater are the Radiant by Hagen, or even the old Metaframe heaters. Sometimes these heaters are all some aquarists can fit or afford on their tank (although Thermostatic heaters have come down in price a lot), but I have seen many an aquarist cook their fish with these, as subtle changes in the dial often over correct and a sudden ambient warm spell is often not corrected for.
With these heaters it is imperative that the water level is kept up to the proper level as marked on the heater or they may crack, it is also important to check these for seasonal variations (Summer/Winter), as these heaters adjust poorly for these.
These should not be used in a room or garage with wide temperature swings as they will not generally adjust properly. Adjustments with these heaters should be made at no more than 1/8 turn at a time then wait for about two hours before the next adjustment.
As with other heaters it is a good idea to place the heater in the tank and wait for 30 minutes before plugging in (although this is less important with these automatic heaters).
Adjustments should be made very gradually and it is easier to adjust these heaters if you start out at our near the desired temperature, otherwise you may be in for a roller coaster of adjustments.
OTHER AQUATIC HEATING DEVICES; Including Under Gravel Mini Heaters:
As for heating betta in a small tank or bowl, this can be difficult with even the smallest aquarium heaters as they tend to be less accurate in very small volumes of water.
One new method for heating bowls or small aquariums under 5 gallons are the Hydor Mini Undergravel Heaters.
These heaters are completely submersible, easy to hide in mini tanks and bowls and safe even under gravel. There is no controller for this type of heater, instead the Mini undergravel heater simply increases the ambient surrounding temperature a certain number of degrees based on the volume of water.
For example, the Hydor 7.5 watt Mini Heater will increase temperature 5 degrees F (2.5 C) for a 2.5 gallon aquarium.
Product Resource: Hydor Mini Undergravel Heaters
I have used (also for my clients) infrared reptile lamps or infrared heating elements placed in desk lamp over the tanks with the distance set according to the temperature desired (the infrared heating elements are generally more pricey and not worth the extra money for a fish, unlike a reptile).
The distance will need to vary based on ambient room temperature. The nice part about using these reptile infrared lights is that they do not interfere with the day/night cycle of the fish the way a white light or even a blue light will.
These are actually quite accurate when used correctly.
When choosing the right heater you need to factor your budget, tank size, fish size potential, ambient room temperature variation, and temperature sensitivity.
For example: a 10 gallon (35 liter) aquarium with platies and guppies would probably be fine with an inexpensive Automatic Heater, the same for a small Betta Tank. But if this tank was in say a shed where temperatures vary greatly, even this example would be better of with a Preset Submersible heater (for Bettas I have also used infrared reptile lamps in desk lamps to maintain temperature successfully while still allowing day/night cycles).
Another example would be fish such as Oscars; with Oscars I would recommend the stainless steel or Titanium heaters as these fish can get rambunctious.
A third example would be marine fish; marine fish generally are not accustomed to much if any temperature swings so a Preset (thermostatic) heater would also be suggested here.
Finally for any larger aquarium (40 gallon +), a Preset heater just makes more sense in my opinion.
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*Aquarium Silicone Sealant; USDA 100% Fish Safe
100% Fish Safe, USDA & Agricultre Canada approved.
The same CANNOT be said for Hardware Store brands!!
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*Aquarium Information, Directory
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