AA Aquarium Green Killing Machine Internal UV SystemUV sterilizers are becoming more and more popular in the aquatics industry, and for good reason! These handy gadgets are able to help treat a large variety of free-floating parasites, bacteria, fungi, and algae in your water.

UV sterilizers are an excellent tool, but they are not a cure-all, so it’s important to identify what kind of problem you’re having in your tank, pick a product that fits your tank best, and then get your new UV sterilizer up and running. We’ve created these reviews of UV sterilizers to take the guesswork out of these products for you.

This category of aquarium equipment can be confusing and finding out what you need can be difficult, so we’re here to help you out!divider1- goldfish

A Quick Comparison of Our Favorites

Image Product Details
Best Overall
Winner
Aquatop Hang-On Back Aquarium UV Sterilizer Aquatop Hang-On Back Aquarium UV Sterilizer
  • Sterilizer
  • HOB filter system
  • Freshwater or saltwater
  • Best Value
    Second place
    AA Aquarium Green Killing Machine UV Sterilizer AA Aquarium Green Killing Machine UV Sterilizer
  • No special plumbing or tools needed
  • Two sizes up to 120 gallons
  • Quiet operation
  • Premium Choice
    Third place
    SunSun HW-304B Aquarium UV Sterilizer SunSun HW-304B Aquarium UV Sterilizer
  • Up to 150 gallons
  • Powerful UV sterilizer
  • Built-in sprayer bar
  • SunSun Hang-On Aquarium UV Sterilizer SunSun Hang-On Aquarium UV Sterilizer
  • Energy-efficient
  • Three-stage filtration
  • Adjustable water flow
  • Coospider Sun JUP-01 Aquariums UV Sterilizer Coospider Sun JUP-01 Aquariums UV Sterilizer
  • Up to 80 gallons
  • With filtration abilities
  • Housing can be opened
  • The 10 Best Aquarium UV Sterilizer Styles – Reviews 2021

    1. Aquatop Hang-On Back Aquarium UV Sterilizer – Best Overall

    Aquatop Hang-On Back Aquarium UV Sterilizer

    The Aquatop Hang on Back Aquarium UV Sterilizer is our best overall pick because it is an excellent HOB filter with a built-in UV sterilizer. It is available in three sizes for tanks from 10-40 gallons, so larger tanks may require more than one filter. It can be used in freshwater or saltwater setups.

    This filter includes a self-adjusting skimmer, helping to clear contaminants from the water and improve oxygenation. Since this UV sterilizer is built into the HOB filter, no additional connections or plumbing are needed to get the full benefit of the UV sterilizer.

    This kit comes with a complete HOB filter including bio-foam, adjustable intake, and an adjustable water flow knob. The UV sterilizer has a separate power source from the filter itself, so make sure to set aside two outlet plugs for this system. This system is easy to set up and designed to run quietly.

    Pros
    • Sterilizer and HOB filter system
    • Three size options
    • Freshwater or saltwater
    • Self-adjusting skimmer
    • Adjustable flow
    • Adjustable filter intake
    • Includes bio-foam
    • Designed to run quietly
    • Easy to set up
    Cons
    • May require more than one for tanks over 40 gallons
    • UV sterilizer and filter each have a power cord

    2. AA Aquarium Green Killing Machine UV Sterilizer – Best Value

    AA Aquarium Green Killing Machine Internal UV

    Out of the products we’ve reviewed, the AA Aquarium Green Killing Machine UV Sterilizer is the best aquarium UV sterilizer style for the money. This in-tank UV sterilizer has two size options for tanks up to 50 gallons and up to 120 gallons. It mounts to the inside of your tank with a suction cup and does not require any special plumbing or tools.

    This UV sterilizer can be used in freshwater and saltwater tanks. It uses a patent-pending zig-zag water flow to maximize the amount of water it clears, allowing it to sterilizer larger amounts of water in a shorter period of time. This sterilizer works by pumping water through, but it should not be confused with a complete filtration system.

    Due to the opaque black housing, you will not be able to see the UV light, which may make you believe it isn’t working. You also may note a slow flow rate, but these are both normal things. If you give this powerful tank gadget a few days, you will see a significant improvement in your algae problem.

    Pros
    • Cost-effective
    • No special plumbing or tools needed
    • Two sizes up to 120 gallons
    • Freshwater or saltwater
    • Patent-pending zig-zag flow to maximize sterilization
    • Quiet operation
    • Helps improve water flow in the tank
    • Helps improve algae levels within days
    Cons
    • Opaque housing makes it hard to see if the light is functioning
    • Not a complete filtration system
    • Will need its own plug-in since it is not part of a system

    3. SunSun HW-304B Aquarium UV Sterilizer – Premium Choice

    SunSun HW-304B Aquarium UV Sterilizer

    The SunSun HW-304B Aquarium UV Sterilizer is our premium pick for the best UV sterilizer style. This is not only a UV sterilizer but a canister filter as well. This system only comes in one size, but it can handle a tank of up to 150 gallons.

    This sterilizer and filter include four removable filter media trays that can be customized with your preferred filter media. It also includes hoses and different sizes of connectors for you to make sure it’s set up just right for your tank’s needs. This system has a built-in sprayer bar that ensures your tank water is thoroughly oxygenated before being returned to the tank. The powerful UV sterilizer decreases your problem algae and parasites. The UV sterilizer has an exclusive on/off switch, so you’ll be able to turn it on and off as needed without altering your filter flow.

    The canister can hold a large number of different types of filter media and runs quietly. The lid latches securely and the drip-free shut-off tap makes cleaning and maintenance easy and hassle-free.

    Pros
    • Canister filter for tanks up to 150 gallons
    • Four removable filter media trays that are customizable with preferred media
    • Hoses and different sizes of connectors included
    • Built-in sprayer bar oxygenates the water
    • Powerful UV sterilizer
    • Separate on/off switch for UV sterilizer
    • Holds a large amount of media
    • Lid latches into place
    • Drip-free shut-off tap
    Cons
    • Canister filters are larger than HOB and sponge filters
    • More difficult to set up than other types of filters and sterilizers
    • No filter media included

    4. SunSun Hang-On Aquarium UV Sterilizer

    SunSun Hang-On Aquarium UV Sterilizer

    SunSun makes a second appearance on our list with the Hang-On Aquarium UV Sterilizer. This product is a HOB filter with a built-in UV sterilizer. It’s available in two sizes covering tanks from 10-50 gallons.

    This setup includes three-stage filtration in addition to the UV sterilizer. The water flow is adjustable and there is a built-in skimmer to help reduce contaminants on the water’s surface. There are two filter media baskets that can be customized with your preferred filter media. This product can be used in freshwater or saltwater tanks.

    This UV sterilizer and HOB filter is designed to run quietly and is energy-efficient, making a minimal impact on your energy usage over the course of a year.

    Pros
    • UV sterilizer and HOB filter
    • Three-stage filtration with two customizable filter media baskets
    • Adjustable water flow
    • Built-in skimmer
    • Freshwater or saltwater
    • Runs quietly
    • Energy-efficient
    Cons
    • Only available in two sizes up to 50 gallons
    • Skimmer can be noisy if turned up too high
    • Replacement bulb may be difficult to find

    5. Coospider Sun JUP-01 Aquariums UV Sterilizer

    Coospider Sun JUP-01 Aquariums in Tank

    The Coospider Sun JUP-01 Aquariums UV Sterilizer also functions as an air pump, water pump, and filter. This product is not adequate to serve as the main filter in a tank, though. It can be used in tanks up to 80 gallons and is only available in one size.

    Coospider recommends opening the housing to inspect the interior every 1-2 weeks to ensure everything is in working order and no clogs or damage have happened. The company runs each UV sterilizer in water to test its functionality prior to shipping, ensuring you receive a quality product. This UV sterilizer has to be fully submerged underwater at all times while turned on. The motor will burn itself out if it is allowed to run while dry. Since this is a separate product from the main filter, it will need its own electrical outlet plug.

    Pros
    • UV sterilizer with filtration abilities
    • Air and water pump oxygenates and agitates the tank’s water
    • Can be used in tanks up to 80 gallons
    • Each UV sterilizer is tested prior to shipping
    • Housing can be opened to inspect light and interior parts
    Cons
    • Only one size available
    • Cannot be used as the main filter
    • Must be fully submerged
    • Needs its own outlet plug

    6. Jebao 36W Aquarium UV Light Sterilizer

    Jebao 36W Aquarium Koi Fish Pond UV Light Sterilizer

    The Jebao 36W Aquarium UV Light Sterilizer is not ideal for small aquariums but is a great option for ponds, large aquariums, and aquariums with exterior plumbing. This sterilizer can be used in any size tank or pond as long as the filtration system is adequate.

    This UV sterilizer features a 22-foot-long electrical cord, making it extremely convenient for the outdoors. This is a non-submersible pump so it should be kept clear of the pond or aquarium and should not be stored in an area that is prone to flooding. This unit can be installed vertically or horizontally. Jebao recommends replacing the light in this unit every 6-12 months. They also recommend installing this UV sterilizer after the filter to prevent damage and clogs. If this is not possible, a prefilter before the UV sterilizer is necessary.

    Installation is easy and this product is made with universal hose hookups, making it suitable for hoses of multiple sizes.

    Pros
    • Can be used in any size tank or pond
    • 22-foot-long electrical cord
    • Can be installed horizontally or vertically
    • Universal hose hookups
    Cons
    • Not well suited for small aquariums
    • Only available in one size
    • Non-submersible
    • Light should be replaced every 6-12 months

    7. Coralife Turbo Twist UV Sterilizer

    Coralife Turbo Twist UV Sterilizer

    The Coralife Turbo Twist UV Sterilizer is a premium-priced product that is available in multiple sizes that can service small tanks all the way up to 500 gallons. This UV sterilizer is an in-line sterilizer, so it will not work with HOB filters. It can be used in freshwater or saltwater tanks.

    It has a double-walled construction to protect the interior of the product, making it last as long as possible. This UV sterilizer features adapters for multiple sizes of tubing. This is a non-submersible sterilizer and comes with mounting equipment to make it easy to keep out of the way while still being able to access it for maintenance. It’s recommended to replace the UV light every 6 months to maintain efficacy. It does have an indicator light to let you know when the light is working.

    Pros
    • Multiple sizes for tanks up to 500 gallons
    • Freshwater or saltwater
    • Double-walled construction
    • Includes mounting equipment
    • Indicator light
    Cons
    • Premium price
    • Non-submersible
    • In-line so cannot work with HOB filter systems
    • Light should be replaced every 6 months

    8. Flexzion 9-Watt UV Sterilizer

    Flexzion 9 Watt UV Sterilizer Light 110V Water

    The Flexzion 9-Watt UV Sterilizer is an in-line sterilizer that is available in one size for 50-2000 gallons. Aquarium filtration systems may not be powerful enough for this UV sterilizer, though, so this product is best suited for ponds. It is a non-submersible, in-line UV sterilizer.

    This product includes hose adapters, making this functional with more than one size of hose. It is not functional for small hoses, though, and cannot be used with hoses smaller than ¾”. It has an on/off switch, but the light will not function if out of the housing, so it’s difficult to see if the product is working. This UV sterilizer has a somewhat complicated installation, so you may need some knowledge of plumbing to install it correctly.

    Pros
    • Works for ponds up to 2000 gallons
    • Includes hose adapters
    • On/off switch
    Cons
    • Non-submersible
    • Smallest hose connection is ¾”
    • Light will not function outside of the housing
    • Complicated installation
    • Aquarium filtration systems may not be powerful enough

    9. Odyssea UV Pro Ultraviolet Sterilizer

    Odyssea UV Pro Ultraviolet Sterilizer Aquarium Filter

    The Odyssea UV Pro Ultraviolet Sterilizer is an in-line, non-submersible UV sterilizer that does not have an on/off switch, so it must be plugged in for use and unplugged when finished. It does not include hose adapters and cannot be used with hoses smaller than ¾-inch. This is available in one size for tanks up to 55 gallons but does require external plumbing so it will not work with a HOB filter system. It can be used for freshwater or saltwater tanks.

    This UV sterilizer includes mounting equipment but may be difficult to mount. It does require some plumbing knowledge to install. It does not include any hoses or pumps. It does have an adjustable-rate switch and an indicator light, showing you when it is working.

    Pros
    • Freshwater or saltwater
    • Indicator light
    • Adjustable-rate switch
    Cons
    • No on/off switch
    • No hose adapters
    • Non-submersible
    • In-line so cannot work with HOB filter systems
    • Complicated installation
    • Only works for systems up to 55 gallons
    • Smallest hose connection is ¾”

    10. Aqua Hang on UV Sterilizer

    Aqua UV 15 watt Advantage

    The Aqua Hang on UV Sterilizer can be used in saltwater tanks up to 75 gallons or freshwater tanks, ponds, or water features 200-500 gallons. This UV sterilizer is a non-submersible unit. It is made so that it can be hooked into the water return of an external filter, turning this UV sterilizer into the water return. The water return is shaped into a small hook that allows this unit to be hooked over the edge of a tank or a sump.

    Since the hook is the water return, it cannot be removed or turned to make it not hook-shaped. This shape design does limit its uses for both tanks and ponds. It also means that this unit cannot be mounted under a tank or at an angle. This UV sterilizer only includes one hose adapter.

    Pros
    • Freshwater 200-500 gallons or saltwater up to 75 gallons
    • Can hook onto tank or sump
    Cons
    • Non-submersible
    • Only recommended up to 75 gallons for saltwater but not less than 200 gallons for freshwater
    • Water return is built into the plastic hook
    • Cannot be mounted
    • Only includes one hose adapter
    • Hook shape limits uses

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    Buyer’s Guide

    Types of Available Options
    • Submersible vs. non-submersible: Submersible UV sterilizers will not function correctly if they are not submerged in the tank or pond. Non-submersible UV sterilizers cannot be submerged underwater. If they are submerged, they can break or become an electric shock hazard.
    • In-line vs. built-in vs. separate: In-line UV sterilizers are a great option for larger tanks because they are installed in the hoses of an external filter, like a canister filter or sump setup. Smaller tanks usually have internal filters, sponge filters, or HOB filters, and do not need externally plumbed filters. For smaller tanks, built-in or separate UV sterilizers are a better option. These can be built directly into a HOB filter or sold as an individual unit that can be separately installed into a tank the way you would install a heater.
    • One power source vs. two power sources: In-line and separate UV sterilizers will require their own electrical outlet plug. Some built-in UV sterilizers run on the same power source as the filter system while others need a separate plug dedicated just to the UV sterilizer.
    • Sizes: UV sterilizers are available in a whole host of sizes, for tanks as small as 10 gallons all the way up to ponds that are a few thousand gallons.
    • Freshwater vs. saltwater: Most UV sterilizers can be used for freshwater and saltwater setups, but it is always a good idea to verify this prior to purchase. Products designed specifically for freshwater setups can quickly be ruined by saltwater.
    Factors to Consider
    • Your current setup: If you currently have a HOB filter with no intention of switching to a canister filter system, then an in-line UV sterilizer likely isn’t going to work for you. If you’re using a canister filter, then using an in-line UV sterilizer will likely be more effective for your tank than adding a built-in or separate sterilizer.
    • What you want a UV sterilizer for: Some people are interested in UV sterilizers because they believe they will fix all of their water quality issues. However, UV sterilizers aren’t made to eliminate every type of parasite, fungus, or algae. UV sterilizers also aren’t made to fix water problems like high ammonia levels. In fact, the introduction of a UV sterilizer can raise ammonia levels due to large-scale die-offs of algae. Identifying the problem you are wanting to treat before investing in a UV sterilizer will ensure you get the right product for your needs.
    • What kind of algae or parasite problems you have: Are you looking to get a UV sterilizer to help maintain already crystal-clear water or is your tank already green? Do you want to keep your tank free of parasites or do you already have parasites present? Many of the separate and built-in UV sterilizers are not powerful enough to eliminate a problem that has already gotten out of control, but they can help maintain the health and clarity of already good-quality water. Many of the in-line UV sterilizers are more powerful and will more effectively clear up a water issue that you already have.
    • What kind of maintenance you are willing to do: Routine maintenance of any tank equipment is good practice, but do you want a product that you’ll need to take apart and clean out every week or a product that can go longer periods of time without cleaning and maintenance? Do you want a more powerful light that needs to be replaced every 6 months or a less powerful light that only needs replacing every 12 months or so?
    What a UV Sterilizer Will Treat What a UV Sterilizer Won’t Treat
    Free-floating algae particles Hair algae
    Free-swimming parasites i.e., ich, velvet, trichodina, myxozoa Parasites that are on or in your fish
    Free-floating microalgae Algae on rocks, gravel, glass, and decor
    Free-floating bacteria i.e. streptococcus, pseudomonas, flavobacterium Bacteria that have already infected your fish
    Fungi in the water i.e. mouth rot, fin rot, cotton-wool disease Fungal infections that have already made your fish sick
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    Conclusion

    Now that you know what you’re looking for, which product do you like the best for your tank setup?

    Our best overall pick, the Aquatop Hang-On Back Aquarium UV Sterilizer, made the #1 spot because of all its great features, including being a UV sterilizer and HOB filter all in one, plus a skimmer. The best value product we chose, the AA Aquarium Green Killing Machine UV Sterilizer, was our #2 pick because of its patented zig-zag water flow, quiet operation, and cost-effectiveness. Our premium pick was the SunSun HW-304B Aquarium UV Sterilizer because although it has a premium price, it also has premium benefits, including being built into a canister filter with four customizable filter media trays and a built-in sprayer bar.

    Remember that UV sterilizers are a tool to help improve your overall water quality, but they will only be able to eliminate free-floating problems in your water. If you have sick fish, they will need treatment in addition to sterilizing the tank.

    We put these reviews together to take the guess-work out of choosing the right UV sterilizer for your tank to save you time and money.


    Featured image credit: AA Aquarium Green Killing Machine Internal UV System, Chewy