Achieving the perfect environment for your fish is an ongoing challenge that constantly occupies any fishkeeper’s mind. Do my cichlids have enough rocky coverage to provide territory markers? Do I have the right type of fish food for both the top feeders and bottom dwellers? Is the water temperature a good fit for the species in my tank? These are all things that beginner and experienced fishkeepers may ask themselves - and for the last one in particular, the answer of ‘no’ can spiral into an even longer list of aquarium heater questions.
With so many water heaters available to fishkeepers, and advice changing depending on tank size, species types, time of year and more, it’s easy to feel a little overwhelmed. Fortunately, we’re here to help simplify everything and guide you towards making the best decisions for your tank. So, if you’ve already asked yourself the first question, and run into all the rest around buying an aquarium heater, stay with our experts as we share all the answers.
Do I need a heater for my fish tank?
As frustrating as it may be not to have an easy answer, there’s not an easy ‘yes’ or ‘no’ response to whether or not aquariums need a heater. This is because whether you need a heater in your fish tank depends on two main factors: the temperature of your tank’s water and the preferred water temperature of your fish.
The temperature of your tank naturally fluctuates, especially as we move through the seasons. So, while you may not need a heater to regulate your water temperature through the more temperate seasons of spring and autumn, when it comes to the sometimes blisteringly cold UK winters, a heater may become a necessity. If your water drops below safe temperature boundaries for your tank inhabitants through winter or even during cold nights in other seasons, investing in a heater will be necessary. However, if you have a warmer, better insulated house that protects your tank from these fluctuations, you might be able to cope without one.
The preferred water temperature of your fish will change not just depending on the species of your fish, but also how hardy they are and what kind of fluctuations they can withstand. For the most part, fishkeepers who’ve chosen to stock their tank with tropical fish, such as tetras, bettas and guppies, will require a heater to bring their water temperature up to a safe, warm level, while those who’ve chosen cold water fish specifically, such as loaches, shrimp and killifish, won’t need one. Hardier species such as goldfish (a beginner fishkeeper’s favourite thanks to their easy-to-care-for nature) can cope with seasonal changes and have a wider temperature range that they can survive in, but we’d still recommend erring on the side of caution and extra safety and adding a heater to their tank set up - especially if their tank is placed next to a window, in a drafty space, or in an older house.
What are the benefits of a heater in an aquarium?
While there are situations in which some fishkeepers don’t need to buy an aquarium heater, you may have heard some experts advise that you should get a water heater anyway. This is because having a heater for your tank provides an extra layer of protection and safety for your fish that justifies the extra cost of buying one. By reducing fluctuations and maintaining a constant and comfortable temperature all year round, you get the following benefits:
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Improved fish happiness: Just because some fish can withstand a wider range of temperatures, it doesn’t mean that they should. All fish regardless of their hardiness levels are happier in a more consistent environment, and even the hardiest of fish can’t survive sudden temperature changes.
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Lowered fish stress levels: As cold blooded animals, fish are completely reliant on the temperature of their environment being suitable for their survival. When living in constant and appropriate environments, their stress is also more easily maintained at a safe, low level.
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Lowered risk of illness: Happy, non-stressed fish are naturally healthier and are able to maintain a stronger immune system - just like humans. So, if you keep your tank water at safe levels, you’re giving your fish the best chance to fight off any infections or illnesses.
What type of aquarium heater do I need?
If you’ve decided that investing in an aquarium heater is the right choice for your tank, the next question you’ll need to ask yourself is what kind you want. There are four main types of tank heater, all of which have their own benefits and disadvantages, and are available at a range of price points to suit your budget. Below, we’ve broken down each of these options, and included some recommendations for the best heaters by category to make sure you’re spending your money on a high-quality option that will last.
Traditional aquarium heaters
Traditional heaters remain one of the most popular choices for aquarists due to their affordability and simplicity. Effectively a glass tube with an internal heating element, these types of heaters work by heating the water in its immediate vicinity which, combined with good water flow, circulates around the tank to raise the overall temperature.
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Placement: These are internal heaters which must be placed inside the tank. It's also best to position the heater next to the filter as this can help to distribute the water around both the heater and the aquarium.
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Cost: Due to their simplicity, traditional heaters are usually cheaper, ranging from around £20 to £30, depending on their wattage.
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Benefits: Traditional heaters are the most affordable option on the market, making them an ideal choice for fishkeepers on a budget or who are only looking for an easy solution to use during the winter.
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Disadvantages: Not the prettiest addition to a fish tank, traditional heaters can spoil your view of your tank a little, causing some fishkeepers to try to obscure it from view. This is fine to do, but make sure you can always see the light which informs you that the heater is operational, and ensure that you position the heater so that it can be removed/replaced with ease – if it does fail, you don’t want to have to strip down your entire aquarium to swap it.
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Recommended traditional tank heater: The Juwel Aquarium Heater is available in a range of wattages to suit your tank’s heating needs (we cover working out what wattage to buy for your tank size in the next section of this blog) and is an affordable heating solution.
Juwel Aquarium 200w Heater, £29.80
Digital aquarium heaters
Increasingly popular among aquarists who value accuracy and enhanced control in their aquarium, digital heaters have additional features which help monitor and adjust water temperature safely. An upgrade on the traditional heater, their digital evolutionary cousins are usually made from plastic, include more accurate sensory systems for taking temperatures, and feature a digital display for more easy readings.
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Placement: These heaters work best when placed in close proximity to your filter or water pump so that the water can be constantly circulated past the heater.
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Cost: A little more expensive than traditional options, digital heaters cost between £30 to £50. As with other heater models, this will depend on brand and wattage.
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Benefits: Due to being fitted with a microprocessor instead of a bimetallic strip (as traditional heaters use), digital heaters provide significantly improved levels of control and accuracy.
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Disadvantages: For most fishkeepers, the higher price of a digital heater can be a sticking point when making a choice. However, if you have a little room in your budget, the improved reliability is definitely worth investing in.
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Recommended digital aquarium heater: The Fluval E Series of Advanced Electronic Heaters is one of our favourites for digital heaters. They have built-in thermostats and dual temperature sensors for improved reading accuracy, and the colour indicator which instantly alerts you when safe temperature bounds are exceeded.
Fluval E 200w Advanced Electronic Heater, £41.99
Titanium aquarium heaters
Another type of internal aquarium heater, titanium heaters are the next level up in temperature control and accuracy. Extra-efficient due to their better internal heat conductors and titanium casing, these can be paired with a temperature controller or thermostat (usually sold separately, depending on the model) in order to effortlessly control your water temperature.
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Placement: As with other internal heaters, titanium heaters need to be placed inside your tank and close to the main water flow to ensure better circulation of heated water.
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Cost: Titanium heaters themselves can cost anywhere between £50 to £80, depending on the wattage, while the price for a heater with a controller starts from around £60.
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Benefits: As titanium heaters usually require an external temperature controller, you can also choose to hook up an aquarium chiller to the same system, making year-round heating and cooling much easier.
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Disadvantages: Naturally, creating a full temperature control system with a titanium heater, temperature controller and water chiller is more expensive than only buying a heater, so the initial cost is more. However, combining these elements will save you time in the long run, and even money if you’re keeping expensive fish and corals at a safe temperature year-round.
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Recommended titanium aquarium heater: The D-D Titanium Heaters range includes wattages ranging from 200 - 600W, and can be purchased alone or with a controller included, depending on your current equipment.
D-D Titanium Heaters with Controller, £62.95 (200W)
External aquarium heaters
Also referred to as ‘in-line heaters’, external aquarium heaters are units which help to heat tank water from outside of the tank. Though removing the sometimes unsightly internal heaters from view is a big benefit, these external heaters will only be suitable for your tank if you have an external canister filter in which to fit it into.
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Placement: External heaters are for use alongside canister filters and sump tanks, and placement instructions will depend on the brand of each element.
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Cost: While heater and filter combination units can range into the hundreds for cost, external filters can be found for around £50 to £60.
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Benefits: Beyond being conveniently hidden away to improve your tank view, external aquarium heaters also provide a more consistent temperature as it is circulated by the filter’s pump before re-entering the tank.
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Disadvantages: In-line tanks do carry a risk of overheating if they aren’t turned off while pump is off as water isn’t passing through the system. Many systems do have additional safety precautions in place to limit this, but it's always best practice to turn it off when needed.
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Recommended in-line aquarium heater: The Hydor ETH External Heater is one of the most popular external heaters on the market, with a self-limiting PTC heating element protecting against overheating, while the PTC technology efficiently and effectively heats the tank's water as it passes through the system.
Hydor ETH External Heaters, £54.50 (300W)
What size heater do I need for my fish tank?
The last question you need to ask yourself before taking that last step and buying an aquarium heater is what size do I need? Heaters are designed to provide a certain wattage output, and should be purchased to suit the size of your tank. As a general rule, you should provide 1 watt of power for every litre of water.
This means that, if you have a 100L fish tank, like the Aqua One AquaNano 60 Aquarium, you should have a heater that provides a total power output of 100W. There’s also a case to be made for buying two separate heaters that add up to your desired output, as these can help to provide an additional safety net in the case that one of your heaters fails, meaning that the temperature drop will be steadier and more even, giving you time to replace the broken unit.
Find an aquarium heater at Aquacadabra
Here at Aquacadabra, we have a full range of aquarium heaters, from internal glass, titanium and digital heaters, to in-line external systems. All from leading brands you can trust, our experts use the same systems in their own at-home tanks so you can be confident that you’re getting the best equipment for your aquarium, no matter which type or size you go for.
If you’re looking for more advice on how to control the temperature in your tank, take a look at our other blogs on What temperature should my fish tank be? and How to Cool your Aquarium, or take a look through our full range of Beginner’s Guides.