Aquarium Heaters Buying Guide
An aquarium heater is a must for any fish owner with a tropical aquatic pet, any other fish species that require warmer temperature, those whose fish tanks are placed in rooms/locations that tend to be colder, and pet owners who live in areas that experience harsh winters.
However, the actual purchasing process can be quite difficult and confusing. Being overwhelmed by the wide variety of products on offer, being ill-informed about the different types of heaters and their specific usages, being unaware of factors such as size, heater placement, installation, and maintenance – these are all problems that can steer you toward making the wrong decision, and ending up with an inferior-quality and/or unsuitable aquarium heater. But what is the best aquarium heater? What features does it need? Are all aquarium heaters submersible? Let’s see.
To aid you in the process, we have compiled a useful buying guide for aquarium heaters, to help you breeze through the selection process and ensure that you are well-informed on all aspects of purchasing a fish tank heater. After you’ve been through our guide, you’ll be able to make the right decision and select a top-quality fish aquarium heater that is perfectly suited to your requirements and the needs of your fish.
Benefits Of Aquarium Heater
If you are wondering “do I need a heater for my fish tank”, this is your answer. Fish may seem like they don’t need much and that’s partially true – unlike more high maintenance pets like dogs and cats, there’s no walks to be taken, no litter to be scooped, and no coat to be brushed.
However, fish do require special, specific types of care, the negligence of which could have fatal consequences. One of the key factors you need to take into account for the health and comfort of your pet is temperature, and the key benefit of an aquarium heater is that it helps fish owners regulate the temperature in an aquarium.
Fish are poikilothermic, or cold-blooded, which means they do not produce their own body heat and their internal/body temperature changes according to the temperature of their surroundings. They are sensitive to the environment and need a specific external temperature in order to be able to survive in fish tanks.
The temperature fish require depends on their species too – bettas, and other types of tropical fish, for example, need warmer water temperatures in order to survive. While some fish are able to survive in room temperature water, there is no guarantee that the water will remain at that temperature, especially if you live in an area that experiences harsh winters. This is why an aquarium heater is not only beneficial but necessary for all fish owners, regardless of the species of the fish.
Aquarium Heater Size Calculator & Guide
Aquarium heaters come in a wide range of sizes, and determining the right size for your aquarium is a crucial step of the decision-making process. It may seem like a daunting task involving complicated calculation, but we’ve broken it down for you and compiled a simplified aquarium heater size guide and an aquarium heater size calculator.
Basically, calculating the correct heater size for your aquarium requires two simple points of information – the temperature of the room in which your aquarium is placed, and the volume of water in your tank, i.e. tank capacity.
First, to determine the aquarium heater wattage you require, use your aquarium’s capacity/volume – calculate 2.5 to 5 Watts per gallon of actual water volume in your fish tank. For example, a 10-gallon tank will require a heater size of 25 Watts.
Next, determine the amount of heating you need – this can be calculated by subtracting the average temperature of the room in which the aquarium is placed from the temperature you want your aquarium water to be. For example, if the average temperature in the room the aquarium is located in is 62 degrees Fahrenheit, and you need the water in the tank to be at a temperature of 79 degrees Fahrenheit, the amount of heating you require is 15 degrees Fahrenheit.
Then, proceed to use the chart below to determine the heater size/Wattage you need. Find your tank volume (i.e. capacity) on the left-hand column, and then look for the column which lists the amount of heating you require (which you previously calculated). If your heating requirement is in between the levels listed, simply move to the next larger size.
(Keep in mind that when tanks are on the larger side, or temperatures are on the lower side, you might need to use two heaters, spaced far apart to ensure even heat distribution throughout the tank).
Tank volume – Heat 9°F/5°C – Heat 18°F /10°C – Heat 27°F /15°C
5 gallons/25 liters – 25 Watt – 50 Watt – 75 Watt
10 gallons/50 liters – 50 Watt – 75 Watt – 75 Watt
20 gallons/75 liters – 50 Watt – 75 Watt – 150 Watt
25 gallons/100 liters – 75 Watt – 100 Watt – 200 Watt
25 gallons/100 liters – 100 Watt – 150 Watt – 300 Watt
25 gallons/100 liters – 150 Watt – 200 Watt – 2x 200 Watt
25 gallons/100 liters – 200 Watt – 250 Watt – 2x 250 Watt
25 gallons/100 liters – 250Watt – 300 Watt – 2x 300 Wat
If you’d rather obtain a quick, automatic answer for the heater size you need, you can use a calculator such as this one, or this one, to determine the most suitable heater size for your aquarium.
Where To Place The Fish Tank Heater
The purpose of an aquarium heater is to heat up the tank – therefore, the aim of correct heater placement in a fish tank should be even and uniform heat distribution. If you are wondering “where to place aquarium heater”, here are some tips for fish tank heater placement.
Ideally, the best place for an aquarium heater is that a heater should be placed as close as possible to the water flow without obstructing it – e.g. the outlet or inlet from your filter, or horizontally directly above the gravel close to the filter discharge if it is a fully submersible heater. The main method for heat transfer in an aquarium is circulation, and when water flows past the heater, heat is dispersed quickly and more evenly throughout the tank. Of course if your tank is large, consider placing two smaller heaters at opposite ends, as this will also ensure more even heat distribution.
Aquarium heater placement also depends, largely, on the type of heater you purchase – for example, a submersible heater will be placed inside the tank, an immersible/hanging heater will be hung off the top edge of the fish tank, substrate heaters will be buried in the aquarium gravel, in-line heaters will be connected to external plumbing, and in-sump heaters will be connected to the sump.
For internal heaters (which are placed inside tanks), some general placement precautions would include avoiding placing the heater close to décor, or placing it in a way that fish might trap themselves or get burnt.
For external heaters, ensure all pipes/connections are properly connected, and avoid placing them in a manner that might lead to them being disturbed or knocked about by passersby – they should be placed safely out of harm’s way.
How Much Electricity Does An Aquarium Heater Use?
Most fish owners will have concerns about the amount of electricity that an aquarium heater consumes, since it needs to be plugged in and remain turned on at all times.
There is no sure way of knowing exactly how much electricity aquarium heaters generally consume – this depends on a variety of factors, such as the type of heater you choose, the brand/model of your heater, the size of your tank (the larger it is, the more expensive it will be to keep heated), and even the species of your fish (tropical fish require warmer temperatures, leading to more expense).
However, by using the size of your tank, and the temperature at which you set it, you can gain a rough idea about the amount of electricity your aquarium heater might be using. For example, a tank with a capacity of 30 gallons, when heated to 72F, will consume about 110 kWh per year. A tank of the same size, when heated to 82F, will consume around 440 kWh per year.
Types Of Aquarium Heaters
While they all have the same function – i.e. to warm up the water in your fish tank – aquarium heaters come in different types. Generally, there are two main types of aquarium heaters – internal heaters (which are installed inside the fish tank itself) and external heaters (which are located outside the fish tank).
There are three types of internal heaters – immersible/hanging, submersible, and substrate – and three types of external heaters – in-line, in-filter, and in-sump. However, all types require a thermostat, to allow pet owners to adjust the temperature as desired. Here, we’ll discuss some of the key characteristics of each type, so you can determine which type best suits your requirements and the needs of your aquatic pets.
These types of aquarium heaters are generally the least expensive type, and most aquarium kits come equipped with this type of heater.
Immersible heaters are also known as hanging heaters, since they are positioned so they hang off the edge of the top of the aquarium (generally at the back), while the heating element (usually a glass tube) is placed in the water. The temperature controls remain outside the water.
An opening in the aquarium hood is required to install this type of heater (most hoods already have an opening to accommodate this type of heater).
While the price makes them an attractive option, care needs to be taken for the safe usage of immersible heaters. They need to be installed securely, to ensure they do not get knocked about or bumped into, as this can cause the glass covering of the heater to break, leading to electrocution, and possibly even a fire.
These types of heaters are also best suited as freshwater aquarium heaters – saltwater can cause corrosion, and lead to electrical shorts.
Submersible Aquarium Heater
These are generally the most popular type of aquarium heater. Since they can be fully immersed in the water, they tend to be more effective heaters than the hanging variety. They are usually installed with the aid of suction cups, and can be positioned lower down in the tank – vertically, horizontally, or diagonally. However, care needs to be taken so they do not actually touch the gravel or any other décor pieces, as this will interfere with heat conductivity. They should also be positioned so fish cannot get trapped against them or burned.
Some submersible heaters have an internal thermostat, while some come with an external temperature controller (these tend to be more convenient). While they are pricier than the hanging variety, their effectiveness makes them well worth the price. In addition, the smaller-sized varieties can easily be concealed, for aesthetic purposes.
These are the least common type of internal aquarium heaters in North America, although they are used widely in Europe. Substrate heaters comprise either a coil or a number of cables/wires enclosed in an insulator, which are installed underneath the aquarium gravel or substrate. When turned on, the coil/wires heat the gravel, which then radiates heat to warm the water. When the water reaches the desired temperature, the thermostat switches off.
While this type of heater is bothersome to install (everything needs to be taken out of the aquarium to put them in), they are extremely effective once put into place, and are also great from an aesthetic point of view, since everything is hidden from sight.
Inline Aquarium Heater
An inline fish tank heater is a type of external, self-contained aquarium heater, which is installed in or along the external plumbing for some aquarium equipment (such as a filter). A water pump is generally required to push water out the tank, through a pipe or tube, and through the heater, after which it is warmed and pumped back into the tank.
You can eliminate the need for a separate water pump by hooking an inline aquarium heater up with a piece of equipment such as a trickle filter or UV sterilizer, which will ensure water flow through the heater without a dedicated pump.
These types of heaters can be a bit tricky to install, but they are incredibly effective, and the best part is that both your fish and heater stay safe, since there is no contact between the two.
These types of aquarium heaters come built into the filter system of the fish tank, for added convenience; they are usually incorporated with canister filters and power filters, and are integral to the design and functioning of the filter. As water passes through the filter, it is heated by the heater, and then returned to the tank both warmed and cleaned. Since they are part of the filter, no additional set-up is required, and there are no clunky, additional heaters obscuring the beauty of your aquarium. However, with some models, temperature control may be tricky.
These types of aquarium heaters are submersible heaters that are located in the sump of a trickle filter. The benefits are similar to those obtained with inline aquarium heaters – since the heater is located outside the tank, aggressive fish cannot damage it, nor can it cause injuries or burns to your pets. However, they may be easier to maintain than inline heaters.
These are small-sized heaters that are used to heat small tanks or fish bowls, instead of large aquariums. They come in particularly handy for fish like Bettas, which are sometimes kept in bowls (the ethics of this may be debatable, but is irrelevant here). These types of heaters have recently been introduced, and while they may be convenient, they can be challenging to use, since they may not heat the water fully or effectively.
Heating Freshwater vs Saltwater Tanks
There are no major differences in regards to the heating between a freshwater tank heater and a saltwater tank heater. The only factor fish owners should take into consideration is that the heater they purchase needs to be safe for use in saltwater/brackish water – the best saltwater aquarium heater will be corrosion and rust free. Some designs and materials are ill-suited to saltwater since the water can cause rust or corrosion. Immersible heaters, for example, aren’t the best idea for saltwater tanks, since salt can get into the tube, leading to corrosion, or an electrical short which can be highly dangerous. Generally, the packaging of an aquarium heater will specify which type of tank it is to be used for, and fish owners need to take this into serious consideration when selecting an aquarium heater.
How To Install Aquarium Heater
The installation process for tank heaters differs according to the type of heater you select – the process of installing a submersible heater, for example, will be vastly different from the process of installing an inline heater. Each type of heater comes with its own instruction manual, and these need to be read carefully, for the safe and efficient installation of you heater of choice.
However, here are some general guidelines that can be followed for how to install aquarium heater:
- Start by removing your fish from the aquarium to a safe location, and turning off the aquarium (but do not empty it).
- Examine the location where your aquarium is placed. Check for any surrounding sources of intermittent heat/cold, and any fluctuations in temperature that might occur. If you feel the location does not allow for a steady and comfortable temperature to flourish in the fish tank, consider re-locating the aquarium.
- Next, examine your heater before you start the installation process – ensure that the casing is intact, and there are no signs of cracks, exposed wires, or any other kind of damage. In addition, keep in mind that heaters should not be turned on until AFTER they have been securely installed.
- Scope out the location where you plan to install the heater – it should be an algae-free location where there is plenty of adequate water flow, for optimal operation and uniform heat distribution. If you plan to use internal heaters, you will want to check the insides of the tank, while for external heaters, you’ll need to examine the equipment you will be attaching the heater to. For example, for immersible heaters, you’ll need to look for space at the back and ensure there is an appropriate hole in the aquarium hood. Ensure that your location of choice is clean and intact.
- Next, use the method prescribed in the instruction manual to install/attach the heater. For example, for inline pumps, you will need to hook the heater up to the return lines from external canister filters or sumps; and for a submersible heater, you will need to mount the device on the aquarium walls using suction cups in the prescribed position. Double check to ensure the heater is properly attached.
- When installing, make sure the heater is not obstructing any other equipment, and not blocking the path of your fish. Internal heaters should also not be touching plants or décor (with the exception of substrate heaters, which will naturally be touching the gravel) as this may cause electrocution or fires, nor should they be positioned in such a manner that fish might get trapped against them and receive life-threatening burns. Make sure that there are plenty of other, more attractive places to hide in the aquarium, so your fish don’t feel the need to swim around the heater.
- Allow the heater to rest for 30-45 minutes, especially if it is an internal heater – internal heaters need time to adjust to the surrounding water temperature (if they are suddenly turned on, they may crack). Similarly, you will need to ensure the heater has been unplugged for at least half an hour before you drain the tank and remove it from the water if you choose to do so later on.
- Slip an external thermometer into the aquarium water – this is so you can get a reading from a second source, and ensure that the heater is working correctly. Read and note the initial reading of the water.
- Then, turn the heater on, and adjust it to the temperature you require. Let it run for 24 hours, and check the thermometer every 4 hours, to ensure the heater is working properly. During this time, you will also get a feel for how the heater and its settings work.
- Finally, when you have ensured the heater is working properly, add your fish back to the water.
Note that it is generally recommended to use an aquarium cover – this helps retain heat and prevent temperature variances which can stress your fish out and be detrimental for their health.
If installing submersible heaters in a large tank, consider using multiple units – this allows for more even heat distribution, prevent the units from getting too strained, and allow the temperature to remain steady even if one goes out. Another recommendation is to keep an extra heater or two as a back-up, in case one stops working.
Fish Tank Heater Maintenance
Just as you clean and maintain your aquarium, heaters need regular cleaning and maintenance too. This is essential for their smooth and proper functioning – not only will regular maintenance increase the life of your heater, it will also give you greater peace of mind, ensure the health and well-being of your aquatic pets, and keep both you and your pets safe from hazards such as electrocution or fires. There is nothing worse than discovering your heater has killed your beloved pets owing to a malfunction which caused over/under-heating, and these malfunctions are usually owing to lack of maintenance.
Most obviously, it is a good idea to buy a heater that is of top quality, and easy to clean to begin with. The trickier a heater is to clean, the more likely you are to avoid it, and the more likely that you might break it (tank heaters are very fragile) or disturb its components during clean-up, leading to malfunctions.
Reading the instruction manual that comes with the heater is the best way to get up to speed on how to clean your aquarium heater.
Generally, the first step would be to turn off the heater (make sure you use a replacement heater to keep the water at a comfortable temperature for your fish while you go about the cleaning process). Next, you will need to use the recommended equipment and prescribed procedure to clean the heater. It is especially important to clean regularly if you have a saltwater aquarium heater (salt can build up inside heaters, leading to corrosion, overheating, and electrical shorts), and remove all build-up such as algae. Once the cleaning process is completed, the heater can be reinstalled and used.
During usage, consider using a heater guard to protect your heater and avoid breakage. Do not ever attempt to take it apart, and if it malfunctions, either discard it and get a new one (this is the best, most recommended option), or take it to a professional instead of attempting to fix it yourself.
In addition, it is always a good idea to keep a spare handy, in case your main heater breaks, especially during crucial times such as winter, or with especially sensitive fish.