Best UV Sterilizers for Aquarium

UV sterilizers for aquariums is a very hotly debated topic. You can find aquarium hobbyists split down the middle when it comes to the subject of UV Sterilizers. The root of the debate seems to stem from the expectation of what a UV Sterilizer can achieve.

In this topic, we will talk about what UV Sterilizers do set realistic expectations, how they function, how to properly install them, and answer some frequently asked questions.

What is UV Sterilizer?

It is a device, a gadget that uses Ultraviolet light from a UV bulb to sterilize the harmful pathogens that may infect the fish in your tank.

Why do you need a UV Sterilizer?

In a closed ecosystem like a water tank, pathogens like bacteria, protozoans, and viruses can quickly spread and if not eradicated soon, can quickly wipe out the entire population of fish. UV Sterilizers provide you with an extra layer of safety between your fish and these pathogens by damaging the DNA of the pathogens effectively sterilizing them using UV light. These also reduce the growth of algae and Cyanobacteria. In case of an outbreak, these slow down the rate of transmission giving you extra time to come up with a treatment for the disease.

How do the UV sterilizers work?

Most sterilizers have a fairly simple working design. They have a large pipe, a waterproof quartz sleeve and a UV emitting light bulb. By flowing water through the pipe we have time for UV light to encounter the pathogens and effectively sterilize them.

There are three main elements that control the effectiveness of the sterilizer. Strength of the bulb, flow rate or contact time with the bulb and the size of the tank or water which dictates the number of times the water passes through the sterilizer.

Best UV Sterilizers for Aquarium

You can find a variety of sterilizers in the market from various companies. Most of them manufacture UV sterilizers for large aquarium houses and businesses that deal with fish trade. But, now let’s quickly move into a list of the best UV Sterilizers the market has to offer for the aquariums we have at home.

Aa Aquarium Green Killing Machine Internal Uv Sterilizer 9 Watt

The Green Killing Machine or GKM as it is called in short is a favorite among the panel of our editors here.

The GKM is a versatile machine. It is manufactured for treating both freshwaters as well as saltwater aquariums.

The one we are talking about here, the 9-watt model can treat up to a whopping 50 gallons or 200 liters of the tank.

It is completely submersible and sealed to ensure than no water leakage occurs.

It has a 12 Volt Internal UV sterilizer with a power head.

It uses a 9-watt sterilization lamp which can last you a lifetime. But in case, you somehow damage the lamp, the lamp can be separately bought.

The UV bulb is sealed. It has a chambered bulb assembly for high water dwell time and outstanding efficacy. Since it is sealed, you require no gloves, no mess, or no bulb changes at all.

It has a built-in LED indication which helps when the UV Sterilizer needs replacement.

The lamp should be replaced when the LED is turned off.

It has a 12 Volt design which is safe for children too.

It has a massive filtration pump of 200 liters per hour and it has a sponge included.

The water flows in it in a zig-zag pattern and it allows for a longer sterilization time.

The setup of this requires no tubing. It has just one plug to work both the UV sterilizer and filtration.

The assembled unit measures:

Length: 7 ½ inches

Width: 1 7/8 inches

Diameter: 4 inches

It comes with a 3 year warranty on the pump.

It has a UL and cUL listing for safety procedures meaning that it has been evaluated and provided with safety marks in the US and Canadian safety requirements.


  1. It works swiftly on free-floating green algal bloom.
  2. The customer service is wonderful and quick.
  3. The smart design of the sterilizer reduces the chances of leaks and damage to the bulb.
  4. The value for money is best in its class 


  1. The cables are clearly visible in the tank.
  2. While it is not the noisiest sterilizer out there, it also isn’t completely silent as it makes soft hum.
  3. It doesn’t work as wonderfully with the algae that are attached to the surface as it does with free-floating algae.

Rating: 4.5/5

Aa Aquarium Green Killing Machine Internal Sterilizer 24 Watt

If you have an aquarium larger than 200 liters but smaller than 120 gallons or 450 liters, the Green Killing Machine 24 watt UV sterilizer is our choice for the best in class sterilizer.

It has the dimensions of 16.7 inches × 3.6 inches × 3.6 inches.

The size of the sterilizer matters. How big the sterilizer is as compared to the tank matters as the longer or larger volume sterilizers can allow more water passage through them consequently sterilizing all the available water without missing. The 24-watt GKM fits the bill perfectly in this regard.

It has a 120 gallons per hour rated water pump along with an internal UV sterilizer and a powerhead.

It is completely submersible and sealed as to ensure there is no leakage of water.

It has a 24 watt sterilization lamp.

The UV bulb is placed in a kind of a chamber. What this does is that it increases the time of exposure of the water with the UV light and allows for better efficient sterilization.    

Also, the UV bulb is sealed separately from the rest of the parts. This not just increases the life of the bulb but also saves you from the hassle of wearing a glove or having a mess when you clean the equipment.

But you may ask if the bulb is sealed away how exactly am I supposed to know when it needs replacement? Surely, the bulb cannot go on working for a lifetime. True. There is an LED signal placed which tells you exactly when you need to replace the old UV bulb.

The lamp should be replaced when the LED is turned off.

I don’t think it comes as a massive surprise that the GKM 24 watt has a massive flow rate of 440 liters per hour. This allows it to run more water through it per hour than most of its competitors. But it does not compromise on quality for efficiency as it also shares the zig-zag flow of water like the GKM 9 watt. This zig-zag flow of water allows more time for better and more uniform exposure to UV lights.

It is highly reliable. In fact, it comes with a 3-year warranty on the pump.  It also has the UL nad cUL listing.

The installation is as easy as you would like, it requires almost no tools and it can be done within 10 minutes.


  1. It has a higher flow rate with zig-zag flow allowing more water to pass through while not compromising on cleanliness.
  2. The UV bulb is hidden away in a chamber meaning you don’t need to be watchful every second during the cleaning process.  
  3. The lack of pf tubing and sealed bulb pushes the chances of leakage to a minimum.
  4. The features and value you get for the money are exceptional.


  1. The equipment itself may be a bit inconspicuous but hiding the wires inside the tank can be a bit of a difficult job.
  2. With all the huge power and flow rate, comes a soft but audible hum at times.
  3. If you have algal bloom attached to the substrate or inner walls of the tank, it may not work as well as it dies with the free-floating algae.

Rating: 4.5/5

SunSun JUP-01 9W Sterilizer

The JUP-01 is suitable for up to a tank of 75 gallons.

It has dimensions of:

Length: 12 inches

Width: 3.3 inches

Height: 3.75 inches

The pump has a flow rate of 210 gallons of water per hour.

It uses a 9 watt sterilization lamp.

As the name suggests it is a submersible water sterilizer and it allows for simple and effective control of harmful microorganisms.

These compact units are ready to install with no extra tubing or circulation pump being required.

It has a large mechanical pre filter sponge that captures debris to optimize UV exposure.

It has a built-in pump that directs waterborne organisms past the UV-C lamp for clean and clear water.

It can be installed either in a vertical or horizontal position in the aquarium or the sump.

It can be used for freshwater, seawater aquariums, or even garden pools.

It includes a UV unit with a built-in pump and UV ballast, UV-C lamp, mechanical pre-filter sponge, and suction cup monitoring brackets.

The bulb needs to be changed once a year and it offers only 6 months of warranty.


  1. This is a quite simple and effective sterilizer.
  2. It includes suction cup mounting brackets.
  3. It acts swiftly on the algal bloom.
  4. It barely makes noise when it is on.


  1. The bulb needs to be changed annually.
  2. The water flow control is kind of hard to manage.
  3. Once the auction cups are in place they are hard to change places.

Rating: 3.5/5

Aqua Ultraviolet Advantage 2000+ Inline UV Sterilizer 15 Watt

The Advantage 2000+ UV Sterilizer is designed to maintain high-intensity performance in a smaller lightweight housing.

These are ideal for small ponds, aquariums and water features.

Advantage UV’s are slim, lightweight units designed for maximum UV effectiveness.

These will clear your water in 3 to 5 days and sometimes even overnight and keep it that way.

The company affirms that the performance is guaranteed when sized, installed, and operated according to the given guidelines.

The Advantage 2000+, 15 Watt plumbs in line and will sterilize up to  500 gallons of fresh water or 90 gallons of saltwater. In marine fish tanks, but not reef or live rock a flow rate matching those shown in the 75,000 or 90,000 columns is most effective at controlling fish disease.

It has dimensions of: 12 ½ inches × 4 inches × 2 ¾ inches

It has an inlet of ¾ inches barb.

The freshwater sterilizer has a flow rate of 700 gallons per hour while the saltwater sterilizer has a flow rate of 233 gallons per hour 


  1. It offers very good value for money.
  2. Comes with a variety of different sizes of the fitting.
  3. It’s multifunctional and can be placed in a number of places.
  4. The small unit so it doesn’t take up much space.


  1. This particular UV sterilizer is not submersible.
  2. It is made up of quiet things plastic.
  3. It doesn’t come with a powerhead.

 Rating: 4/5

Aqua Ultraviolet 8 Watt Advantage 2000 Inline UV Sterilizer

It has the dimensions of: 13 inches × 4 inches × 2.5 inches

It is designed for in line use. So if you are not a fan of other bulkier and slightly prickly to the eye designs, the inline provides you with easy on the eye aesthetics.

The Sterilizer has a maximum flow rate of 642 gallons per hour.

The Clarifier has a maximum flow rate of 1000 gallons per hour.

It has the freshwater application of 5 to 200 gallon pound.

The saltwater application is however at 70 gallon pound

It has a single UV lamp which is positioned in a housing. The clear Quartz cap lets you see the glow that tells your lamp is on.

It is easy to remove and has a remote power supply.

The slender housing design allows for higher UV dosage.

Just like it’s higher power cousin it has a inlet/outlet of ¾ inch barb.


  1. It offers very good value for money.
  2. Comes with variety of different sizes of fitting.
  3. It’s multifunctional and can be placed in a number of places.
  4. Small unit so it doesn’t take up much space.


  1. This particular UV sterilizer is not submersible.
  2. It is made up of quite thin plastic.
  3. It doesn’t come with a powerhead.

Rating: 4/5

Coralife Turbo Twist UV Sterilizer 3x

The Coralife Turbo twist is an ultraviolet sterilizer designed to eliminate single-celled algae and disease-causing pathogens.

It features the Turbo twist design which functions by guiding the incoming water around the enclosed UV lamp to maximise exposure or what we call as the dwell time for overall efficiency. This extended treatment fully utilises the available UV output and helps maintaining crystal clear water.

The 9 watt model treats up to an aquarium of 125 gallons in size.

It features a power cord of 10 ft length.

The outlet and also the inlet sizes are ½ inches , 5/8 inches barbs.

It has a dimension of 10.75 inches × 3 inches × 4.25 inches

Many users, however, complain of leakage and poor build quality.


  1. This is perhaps the easiest UV sterilizer to set up making it a perfect starting point for a beginner.
  2. It comes with a 12 months warranty.
  3. It does a fairly good job at cleaning algal bloom.
  4. It has a clear window so you can see the bulb is running.


  1. This sterilizer is on the expensive side.
  2. You will need extra tubing to use it as an inline sterilizer.
  3. The unit is quite large.
  4. Many users complain of questionable leakages.

Rating: 3/5

Editor’s choice:

Aa Aquarium Green Killing Machine Internal Line Uv Sterilizer 9 Watts

Here are the factors and characters that make the Green Killing Machine our choice:

  • It has quite a simple installation process, you get this pre-assembled out of the box, which can be easily set up in your aquarium by following the simple quick start-up guide that is available with the back. You just have to connect it according to the guide and it’s ready to go.
  • Unlike many of its competitors, it has an internal design meaning that it is made to be kept inside the tank. The design is quite simple and easily overlooked which is a nice thing as it can be hidden behind the aquarium ornaments.
  • The Green Killing Machine Inline UV Sterilizer eliminates the tubing and consequently leaking outside of the tank.
  • It is versatile in its placement and can be placed both vertically and horizontally.
  • It has a special LED light that signals you whenever the UV bulb requires replacement.
  • The UVC rays can wear away plastic housings and other materials in and around it. To counter that, the bulb is placed inside the housing and is sealed and there is no chance of getting it wrong or any chance of leakage of the UVC lights.
  • The pump itself is rated at 50 gallons per hour but the flow is further reduced with the zig-zag flow within the bulb. This allows the water a long time for UV treatment as the reduced flow improves UV efficiency.
  • It can be used for both saltwater as well as freshwater aquariums.
  • Unlike many of the competitors, the aquarium Green Killing Machine has a UL and CUL certification from both the United States and Canadian safety measurement Departments.
  • It is cheaper and provides the best value for money among its competitors.

How do I choose the right UV Sterilizer for my aquarium?

  The type of you be sterilizer you would want for your aquarium depends upon your tank. And since, all tanks are different so each tank has its own need and it doesn’t make the process of choosing the light UV sterilizer any easier.

Fortunately for us, there are a lot of UV sterilizers in the market to choose from and hence you can, without fail, find a UV Sterilizer to fit your need. The UV Sterilizers are easy to use and easy to install and most of them just sit on the side of your tank like a heater.

The biggest factor that determines what kind of UV sterilizer you would want is the size of your tank. The UV sterilizer world size matters because for a bigger tank you need a stronger pump and a bigger or larger volume So that it can deal with the larger volume of the water present in the tank.

For a smaller tank, however, you might want to consider the size of your equipment. You don’t want the UV sterilizer hindering the space of your fish to swim. Some UV sterilizers are built-in as the part of the filter or can be connected to the filter and they save you a bit of money as well as space that is so vital in a smaller aquarium.

Determining the size of the sterilizer you need you can look for additional features.

For example, our editor’s choice The AA Aquarium Green Killing Machine employs a zig-zag pattern that maximizes the ultraviolet exposure in the water. It also can be used for both freshwaters as well as saltwater while many others are designed to deal with one other.


How to install a UV Sterilizer?

Most UV sterilizers are very simple to install and are installed in a similar way to common canister filters.

Before you begin installing make sure you dismantle the sterilizer and familiarize yourself with the components which will later help you clean the parts.

Make sure to place the UV sterilizer away from other pieces of equipment and decorations, so that nothing blocks the water inlet. But it also needs to be somewhere which is easily accessible so that you can reach it for cleaning.

Some UV sterilizers have the crystal sleeve which is quite fragile and can easily break if knocked so you have to be careful while installing it.

If you have an aquarium UV Sterilizer that works by attaching itself to the filter, place it last in the filtration line so that the water passes through the filter before it passes through the sterilizer.

The filter removes the solids first, maximizing the efficiency of the ultraviolet light.

When you first set the UV sterilizer, make sure it is working. Check that the water is being drawn in and out smoothly and listen to the unexpected noises.

Does it kill useful Bacteria?

It depends. The fact is that the UV sterilizer does not kill enough beneficial bacteria to upset the balance of your aquarium. Some beneficial bacteria tend to float freely and these are the ones that get sterilized by the UV filter.

But many nitrifying and other useful kinds of bacteria live in the filter media which is placed away from the UV sterilizer or you can also save the beneficial bacteria from the UV filter by keeping the feeding grounds away from the UV sterilizer, such as in the sand filter or replacing rocks on the bottom of the pond.

Does the UV sterilizer harm fish?

The ultraviolet rays are not particularly high penetrating waves. So for larger organisms like invertebrates and fish and corals to get majorly harmed by the UV rays they must be under direct radiation from the UV sterilizer and for very prolonged time which does not happen in a normal aquarium.

Hence, the UV sterilizer does not harm fish. However, it may stress the fish a bit when it is first installed and this phenomenon too is not a common one.

How to maintain a UV sterilizer?

Maintenance of the UV sterilizer mainly consists of cleaning it frequently.

As we have discussed earlier, before installing the UV sterilizer you must dismantle it and get familiar with so that it becomes easier for you to clean it. And cleaning must be done as regularly as you clean the filter and the cleaning involves the cleaning of the crystal sleeve and the pump and parts like the bulb if accessible.

Many UV sterilizers require changing of the bulb once a year.


For many of us that maintain proper cleanliness inside out tank, clean the substrate properly and frequently, maintain the cleanliness in the filter and do frequent water changes, UV sterilizer machine can come across as an unnecessary expenditure.

But there are many occasions when a mistake or delay in cleaning can very easily happen and lead to an algal bloom or the unnecessary growth of microorganisms like harmful bacteria or even viruses. In such cases, the UV sterilizer not only provides a safety net for your aquarium water but also in the case of an outbreak it provides you with extra time to search about the diseases and act on the solution since it delays the transmission of the outbreak from one organism to the other organism inside the tank.

Hence you can conclude add a UV sterilizer is ah mindful investment if not 100% necessary one. And in this article, we tell you why it is important, how you should choose one and also give you a review of the products you may find in the market.

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