An aquarium UV sterilizer is a vital device for the proper management of both saltwater and freshwater fish tanks. It supplements the filtration system of an aquarium because of the ability to kill parasites, viruses, algae, and bacteria floating in the water. Another reason for the importance of aquarium UV sterilizer is its ability to control the spread of infections from one fish, coral or invertebrate to another via water. Without these devices, harmful microorganisms could spread out fast and destroy the entire inhabitants of an aquarium or pond.

How do UV sterilizers work?


Aquarium UV sterilizers are fairly simple pieces of equipment. They act very much like a standard pump or submersible filter. Water is drawn into the unit and flows through a chamber where the ultraviolet light bulb is located. The bulb emits an ultraviolet light that bombards the water (and everything in the water) with a powerful dose of radiation. This results in the death of most organic matter that comes into contact with the ultraviolet light. When properly used in the aquarium, algae, bacteria, and even parasites and viruses can be eliminated.

What is key in the proper operation of a UV sterilizer is that the water flow through the unit is not too powerful. The more slowly the water passes over the ultraviolet light bulb, the more the water and its contents are exposed to the radioactive light. If the water flow is too high, the water will not be adequately exposed and it will take much longer to achieve desired results.

The benefits of using UV sterilizers

Ultraviolet sterilizers are most effective when used as a preventative measure. In this respect, UV sterilizers have multiple applications:

Algae and fungus control – UV light counters algae and fungus in two ways. First, by killing off and controlling the spread of organic matter (and thus nutrients) in the water, substances that act as food for algae and fungus in the water are restricted. Second, UV water sterilizers kill off spores and free-floating algae, containing the spread of these nuisances and stunting their growth.

Elimination of green waterGreen water is a very resilient, fast-growing single-cell algae that can quickly overrun an aquarium. Using UV sterilizers is one of the few effective ways of controlling and eliminating this type of algae. For those that keep aquariums that receive ample sunlight or outdoor ponds, they are a practical necessity.

Elimination of cloudy water – If your aquarium suffers from a prolonged cloudy water problem, it is ideal to use a UV sterilization lamp for the tank. The sterilizer kills only the free-floating microorganisms that are in the water flowing through it, so it is absolutely safe for the helpful nitrifying bacteria living on the surface of biological filter media and gravels.

Disease prevention – By eliminating organic matter in the water column (including foreign material that can be accidentally introduced to the water), ultraviolet light reduces the number of potential disease vectors and elements that can worsen water quality and clarity. This also includes the ability to kill bacteria and viruses.

Parasite control – Nearly all free-swimming parasites can be eliminated if they receive sufficient exposure to the ultraviolet light bulb. When combined with proper tank or pond maintenance, it becomes incredibly difficult for parasites to gain a foothold. In cases of existing infection, UV sterilization combined with medication and water changes can quickly dispatch the invading parasites.

Now that you know what aquarium UV sterilizers are, their benefits and how they work, it is time to consider a few of the greatest sterilizers currently on the market. This will steer you in the right direction if you are looking for one to purchase.

Best aquarium UV sterilizers

Image Model Type UV wattage For tanks Our rating
Green-Killing Machine internal 9W up to 50 gallons 5/5
SunSun JUP-01 internal 9W
(other sizes available)
up to 50 gallons 5/5
Coralife Turbo-Twist 12X in-line 36W
(other sizes available)
up to 500 gallons 4.5/5
Aquatop PF15-UV hang-on 5W
(other sizes available)
up to 15 gallons 4.5/5
Grech CBG-800 hang-on 5W
(other sizes available)
20-50 gallons 5/5
SunSun HW304B canister filter 9W
(other sizes available)
up to 150 gallons 5/5
Aquatop CF500-UV canister filter 9W
(other sizes available)
up to 175 gallons 4.5/5

Aquarium UV sterilizer reviews

Green-Killing Machine internal 9W UV sterilizer

  • Green-Killing Machine internal 9W UV sterilizer5 star rating (5/5 by editor)Check on
  • Type: internal sterilizer with power head
  • UV wattage: 9 watts
  • Ideal for: aquariums up to 50 gallons/100 liters
  • Features: LED light indicator for UV bulb replacement.

The Green Killing Machine UV sterilizer offers you the best way to maintain your fish tank without the need of using chemicals. The sterilizer offers radiation at a wavelength of 254nm, it works with a water pump and can handle aquariums up to 50 gallons (200 liters).

It is a fully submersible UV sterilizer with a powerhead in one unit making it versatile, efficient and easy to use. Its design makes water flow through it in a zigzag to maximize the exposure time to powerful UV light that will irradiate any harmful microorganisms such as molds, yeast, bacteria, etc. It is very effective in clearing green and prolonged cloudy water, eliminating bacteria and harmful parasites in the water.

The entire system works in aquarium water like internal filters and is very simple to install without the need of external plumbing. Suction cups are also included for positioning the sterilizer in place. It also features an LED light which signals the need of bulb replacement.

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SunSun JUP-01 9W UV sterilizer with pump

The awesome SunSun JUP-01 9W let you simply and effectively sterilize your aquarium with UV light to eliminate pathogenic microorganism that could interfere with the health of your aquarium pets. It features a flow rate of 210 gph and can handle tanks of up to 75 gallons in capacity. It is ideal for both saltwater and freshwater applications.

The SunSun JUP-01 works by combining a filter pump and a UV light. The pump forces water to flow through the powerful UV light to sterilize unwanted organisms. Besides, a large mechanical pre-filter sponge is included to trap solid wastes before they reach the internal UV light to enhance the radiation effects on microorganisms and protect the pump from clogging.

The sterilizer is safe to your fish, corals, aquatic plants, and people. It is very easy to set up, operate and maintain. The small and compact design allows its ability to be placed in anywhere in your aquarium or sump tank with suction cup mounting brackets.

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Coralife Turbo-Twist 12X in-line ultraviolet sterilizer, 36W

The Coralife Turbo Twist 12X (36 watts) with quartz glass sleeve is one of the best in-line UV sterilizers you can find in the market. The powerful UV light source is produced by a PL-type compact 36W fluorescent lamp, which is strong enough to sterilize home aquariums or small ponds up to 500 gallons.

Its revolutionary turbo twist design ensures the water passing through the device being exposed to more germicidal killing ultraviolet light than that of conventional UV sterilizers. It is perfect for both freshwater or saltwater tanks of up to 500 gallons. It features an indicator light, which lets you know when the device is operating.

The sterilizer is very versatile, easy and quick to install with the mounting brackets included for both hang-on or in-line applications. All you need to do is to connect the sterilizer to a power head (water pump) or include it in the return line of your filtration system (canister filter or Wet/Dry filter). The water pump is not included in the package and you will have to find one that provides a flow rate from 300 to 900 GPH.

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Aquatop PF15-UV Hang-On filter with UV sterilization

Aquatop is well known when it comes to high-quality and affordable aquarium products. The PF15-UV is one of those products. Being designed to have filtration and sterilization capabilities, this versatile filter with UV sterilization offers you a good way to “kill two birds with one stone”. It features an adjustable flow rate of up to 64 gallons per hour making it ideal for small aquariums up to 15 gallons.

The 5-watt UV bulb is capable of neutralizing parasites, bacteria, and algae as well as clarifying your aquarium water. There is an independent UV light power switch for turning on or off the UV light whenever you need. You surely don’t need to turn on the UV light all the time.

Its hang-on design is very convenient to use because you will not need any extra plumbing to get it to work. Moreover, it has a built-in auto-adjusting surface skimmer helpful in cleaning the surface of your aquarium water and promoting gas exchange.

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Grech CBG-800 5W UV sterilizer Hang-On-Back filter

The CBG-800 by Grech is another great choice if you are looking for an external Hang-On-Back filter with UV sterilizer. The filter has an adjustable 211 gph flow rate as well as a surface skimmer designed to get rid of surface films. The 5W UV sterilizer helps to neutralize pathogenic bacteria, algae, parasite and keep your aquarium crystal clear. You can turn the 5W UV sterilizer on or off with an independent switch. It is suitable for both freshwater and saltwater aquariums from 20 to 50 gallons.

Its compact design makes it elegant and easy to install. No tools or extra plumbing required. Some types of filter media (floss, bio-media, activated carbon) are also included for a complete and multi-stage filtration (mechanical, biological and chemical). It is a great unit to set up in your aquarium.

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SunSun HW304B 525GPH Pro canister filter kit 9W UV

The SunSun HW-304B is an external canister filter which is included with a powerful 9 watt UV sterilizer. It owns a flow rate of 525 gph and is suitable for freshwater and saltwater aquariums of up to 150 gallons. Its core features 4 flexible media trays to allow you to add various types of filter media such as mechanical filter pads, ceramic rings, activated carbons and bio balls. It is thus capable of achieving 5-stage filtration including chemical, biological, mechanical and UV stages.

The HW-304B has a convenient self-priming pump capable of eliminating the need for manual siphoning. Its UV sterilizer can help kill algae spores, parasites and bacteria leaving your aquarium water crystal clear for the benefits of your pets. This filter canister with UV sterilizer is worth for the money, it works more than other canister filters but cost less than them.

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Aquatop CF500-UV canister filter with UV

  • Aquatop CF500-UV canister filter with UV4.5 star rating (4.5/5 by editor)Check on
  • Type: canister filter with UV
  • UV wattage: 9 watts
  • Flow rate: 525 gallons per hour
  • Baskets: 4 media trays
  • Filter media: mechanical filter pads
  • Ideal for: freshwater/saltwater tanks up to 175 gallons
  • In this series: Aquatop CF300 (264 GPH, none UV, up to 75 gal), Aquatop CF400-UV (370 GPH, 9W UV, up to 125 gal tanks)

This extremely quiet canister filter has an inbuilt UV sterilizer capable of mechanically, chemically and biologically cleaning your aquarium water for the benefit of your fish. Its 4+1 stage filtration gets rid of all debris and dirt that might be in the aquarium water. It is useful for freshwater and saltwater tanks of up to 175 gallons.

The Aquatop CF500-UV is armed with a 9W UV sterilizer to kill pathogenic organisms in your fish tank. It comes with the necessary piping and plumbing necessary for the installation. It is also very easy to operate and maintain. Besides, it comes with an instruction manual to help with the installation.

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Maintaining UV sterilizers

In order to function properly, UV sterilizers need to be periodically inspected and cleaned. Care needs to be taken when cleaning the ultraviolet light bulb. Some varieties of sterilizers have a quartz-shielded sleeve that protects the bulb and prevents the escape of light radiation. Be sure to properly clean the area of the bulb and re-sheath it with the protective covering.

Always be sure that the UV light bulb is properly covered before turning the device on. Never expose yourself or any part of the body to ultraviolet light.

Ultraviolet light bulbs will need to be replaced regularly to ensure that the unit is functioning properly and to its full potential. Typically, bulbs need to be replaced every six to twelve months.

Ultraviolet sterilizers meet many needs of home aquariums, ponds, and even professional applications. Anyone keeping a large aquarium or pond should have this tool at work for them. UV sterilizers are the single most effective piece of equipment for preventative aquarium health.

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