7 Best UV Sterilizers for Aquariums: Reviews & Buying Guide

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1. Introduction

Dealing with algae is one of the most frustrating challenges aquarists face. Aquarium stores offer a plethora of solutions, from algaecides to filters that claim to eliminate algae, but they don’t always work. A practical and convenient solution used instead by many aquarists is an ultraviolet sterilizer. They’re not the only tool in the toolbox for fighting algae, but they’re a highly useful one.

After experimenting with numerous methods to get rid of algae, I found that installing a UV light was all I ever needed. There are different types of UV sterilizers, like in-line, canister, internal, and HOB UV sterilizers, and each match various tank requirements like tank size and sunlight exposure. I’ve reviewed what are in my opinion the best uv sterilizer for aquarium, even combing through other customers’ feedback so you don’t have to! Let’s dive in.

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2. 7 Best UV Sterilizers For Aquariums

2.1 AA Aquarium Green Killing Machine GKM9W

Tank capacity: 50 Gallons

Dimensions: 4 x 4 x 12 inches

Type of sterilizer: Internal UV sterilizer

Best for: Ease of set up


The AA Aquarium Green Killing Machine UV sterilizer unit is a complete kit that includes a water pump, a few sponge strips, and a UV light, which uses a 9w UV bulb for tanks up to 50 gallons. The UV bulb is fully covered and uses an LED light to signal when the bulb needs a replacement.

Personally, I consider the sponge filter to be more of a backup as it may help trap some waste, but isn’t robust enough to rely on as a full filtration system.

One thing about the AA Aquarium Green UV sterilizer that’s great for beginners is that it’s ready to go right out of the box. You don’t need any additional pipes or tools to run it.

Replacement UV bulbs are sold separately, and the manufacturer includes a 1-year warranty for any factory defects of the product. The manufacturer notes that you don’t have to run it all the time; It can be switched off once the water is clean to increase the durability of the UV lamp.

Customer Sentiments

With an overall rating of 4.3 stars out of 5 (as of date), the AA Aquarium Green Killing Machine UV sterilizer packs a punch. This aquarium UV sterilizer works wonders, clearing out green aquarium water within just a few days, and buyers agree. Some found that the suction cups aren’t firm enough to hold the UV sterilizer, but this is an easy fix.


  • 1-year warranty for factory defects.

  • Ready to operate.

  • Led light to indicate UV lamp replacement.


  • Suction cups can be hit-or-miss.


2.2 Aquatop SP-7 UV

Tank capacity: 75 Gallons

Dimensions: 10 x 3 x 3.25 inches

Type of sterilizer: Internal UV sterilizer

Best for: Mechanical filtration system


The Aquatop SP-7 UV aquarium UV sterilizer is another option that you can easily fit onto the walls of your fish tank. The 7W UV bulb is protected inside a quartz sleeve, making it an efficient choice for freshwater or saltwater tanks of up to 75 gallons. Plus, the included pump has an adjustable flow that pumps up to 126 gallons per hour.

I really like this product’s pre-filter and mechanical filtration system, as I’ve found them to be more dependable compared to ones in other aquarium UV sterilizers. Another feature I like about this unit is its rotatable water spout, is very helpful when you want to change the water outflow direction.

The UV bulb is replaceable, and if you don’t have enough space to fit this in your aquarium, you can attach it to the sump tank instead.

Customer Sentiments

With a rating of 4.1 stars out of 5 (as of date), buyers are happy with the ease of setup for this aquarium uv sterilizer. It’s not particularly easy to take apart during maintenance, but this is a common complaint among most internal UV sterilizers and filters; I’ve personally dealt with this issue often. A bit of extra patience during disassembly goes a long way.


  • Adjustable flow rate.

  • Ready to operate.

  • Rotatable water outflow.


  • None apparent. Not easy to take apart for maintenance.


2.3 Coralife Turbo Twist 3X

Tank capacity: 125 Gallons

Dimensions: 3.5 x 11 x 3.5 inches

Type of sterilizer: In-line UV sterilizer/ HOB

Best for: High efficiency


If you’re looking for a UV sterilizer for a large tank that requires effective sterilization, the Coralife Turbo Twist 3X is an excellent choice. Compatible with tanks up to 125 gallons, this UV sterilizer specializes in removing both harmful bacteria and free-floating algae from the aquarium water, and has a strong, 9w UV bulb.

Something unique about this UV sterilizer unit is that it consists of a unique, twist-flow design for increased contact between the tank water and UV light, which I really appreciate. What’s more, I’ve had trouble with other UV sterilizers not indicating if the lamp is functioning correctly, but Coralife is one step ahead of me on this: The Coralife Turbo Twist has a handy indicator light displaying its operational status.

You can use this unit as an in-line UV sterilizer or an HOB sterilizer, as all necessary parts are provided to attach whichever way.

Customer Sentiments

Out of 330+ ratings, this UV sterilizer has an overall rating of 4.4 stars from 5. Consistent with my own sentiments, many buyers say that this is the best UV sterilizer they’ve ever used, after experimenting with other brands. It successfully eliminates algae blooms in just a few days in freshwater and saltwater tanks. One thing to keep in mind is that it has several components that need assembling, so setup takes time. It also doesn’t come with a water pump, so you’ll need one separately.


  • Can be used as both an in-line or HOB sterilizer.

  • Powerful, increased UV light exposure to water.

  • Replaceable UV lights.


  • Pump not included.

  • Requires assembly.


2.4 Oxyful Non-Submersible UV Sterilizer

Tank capacity: 125 Gallons

Dimensions: 11″ x 6″ x 3″

Type of sterilizer: External UV sterilizer

Best for: Small tanks/Not taking up space in the aquarium


If you have tank that’s at capacity in terms of space, and/or you’re looking for a non-submersible UV sterilizer unit to fit your aquarium or pond, the Oxyful Non-Submersible UV Sterilizer is your best bet.

This unit will operate outside of the water and uses a pump to flow in water, which passes through the UV chamber. The maximum pump flow rate is 396 GP/H, and the pump is purchased separately. The Oxyful Non-Submersible UV Sterilizer can be used in a freshwater or saltwater aquarium, and helps ensure the elimination of harmful microorganisms and algae.

The bulb is advertised as designed for lasting up to one year, and is replaceable. The manufacturer recommends adding a pre-filter or attaching this after the filter, to prevent debris from damaging the quartz sleeve, which is a good tip.

The brand Oxyful offers UV sterilizers with different wattages for various tank sizes; This particular one is 9w, but you can also check out their page for other sizes depending on your tank.

Customer Sentiments

The overall rating from users for this UV sterilizer is 4 out of 5 stars, and most of us agree that it effectively clears algae within a short time. That said, several buyers were frustrated with the set up process, mostly because it didn’t come with instructions. These were probably uber beginners, so I can understand that. If you’re confident with your technical skills and have had these devices before, you’ll be fine:)


  • UV bulb is fully covered.

  • Replaceable bulb.

  • Can be installed vertically or horizontally.


  • Doesn’t include a pump.

  • Lacks instructions.


2.5 Sunsun Hw303B Pro Canister Filter Kit

Tank capacity: 100 Gallons

Dimensions: 10.5 x 10.5 x 16 inches

Type of sterilizer: Canister filter

Best for: Full filtration + UV sterilization


This 9-watt UV sterilizer is part of the Sunsun Hw303B Pro Canister Filter Kit, which provides a complete, super-convenient solution for filtration and UV sterilization. Installing this kit knocks out your filtration needs and UV sterilizer needs in one go.

The UV lamp is connected to the socket, which operates inside the canister filter’s body. There’s a small glass panel over the UV light so you can view the functioning of the light bulb.

I love that this is a complete filter system, including different types of filter media and a self-priming, built-in pump. While UV light kills harmful bacteria in the aquarium, the biological filter media will help grow beneficial bacteria. I find that this canister filter system is well-designed as it uses a clip-on lid and other high-quality components.

Customer Sentiments

This filter system with a UV clarifier is great for both saltwater and freshwater aquariums, and has a favorable overall rating of 4.4 stars from over 1200 customers. We love that this filter operates silently, and that the UV sterilizer has done a fantastic job controlling algae. I don’t think the provided filter media is always sufficient to fill the large media trays, so in my opinion, it’s worth spending a few extra bucks for filter media to operate this filter kit. Plus, we’re reviewing it as a UV sterilizer; Many people already have a filtration system, and this one’s just secondary for them.


  • Complete combination solution that includes UV sterilizer + filtration system.

  • Replaceable UV bulb.

  • Self-priming pump included.


  • Extra filter media may have to be purchased.


2.6 Aqua Ultraviolet Advantage 2000

Tank capacity: 200-500 Gallons

Dimensions: 12-1/2” x 2-3/4” x 4”

Type of sterilizer: External UV sterilizer

Best for: Large tanks or small ponds


I picked this particular in-line UV sterilizer because it’s immensely popular in the aquarium hobby, and for good reason. Manufactured in the USA, the Aqua Ultraviolet Advantage 2000 unit consists of an ultra-powerful 15w bulb, which operates inside a UV chamber to minimize wasted UV light. It’s compatible with relatively large aquariums and small ponds (200-500 gallons).

This unit operates outside the water, and needs a water pump to flow tank water through its UV light before being released back into the aquarium.

Something unique that I spotted in the Aqua Ultraviolet Advantage is its slim UV light bulb, which emits UV rays much more efficiently.

This unit can be used for both freshwater tanks and saltwater tanks. Depending on the size of your tank or pond, you can also check out the larger units the Aqua Ultraviolet brand offers.

Customer Sentiments

With a rating of 4.3 stars out of 5 (as of date), buyers are happy with this ultraviolet sterilizer’s ability to quickly turn murky water to crystal clear. The downside is that because the UV bulb is a slim version, you can’t replace it with more standard sized bulbs. Of course, you can still get replacement bulbs directly from Aqua Ultraviolet as needed.


  • Can be used in extra-large freshwater tanks, saltwater tanks, and small ponds.

  • Won’t take up space in the tank.

  • Efficient UV system for larger use cases.


  • Pumps not included.

  • Replacement bulbs must be from purchased Aqua Ultraviolet.


2.7 Grech CBG Hang-On Back Filter With UV Light

Tank capacity: 10-30 Gallons

Dimensions: 7.6 x 4.4 x 6.5 inches

Type of sterilizer: HOB filter

Best for: Compatibility with nano aquariums


When looking for an ultraviolet sterilizer for a small aquarium, there’s not a ton of options out there. Enter the Grech CBG Hang-On Back Filter With UV Light. As you can tell from the name, its primary purpose is a filter – But is also has a UV light! If you need a good nano UV sterilizer, this is a great option.

The HOB filter system has a 5-watt UV sterilizer, adequate for a tank between 10-30 gallons. It can be used in small freshwater tanks or nano reef tanks, and the UV sterilizer does its job in eliminating free-floating parasites from the tank water and other yicky culprits of algae blooms. The UV light can be manually switched on/off separately without affecting other functions of the HOB filter, which is great.

In addition to the UV light, effective filtration can slow down algae growth because fish waste boosts algae blooms – So the surface skimmer included in this HOB filter, along with biological, mechanical, and chemical filtration, help combat and prevent algae/green water.

Customer Sentiments

Currently, with an overall rating of 4.3 stars from over 270 customers, this is a solid choice for anyone needing a small filter with a UV sterilizer. Buyers are impressed with the performance of the UV filter, which clears the water effectively. Some people didn’t like that there’s no indicator light to display the functioning of the sealed UV bulb. I’d have to agree, but I still think it’s a great option for a UV sterilizer for a nano tank. One design aspect that could be improved is that the on/off switch is located at the bottom of the filter, which isn’t the most convenient location:)


  • Ready to operate.

  • Ideal for nano fish tanks.

  • An adjustable flow rate of water.


  • No indicator light.


3. Our Pick: The Best UV Sterilizer For Aquarium

After comparing lots of brands and other UV sterilizers, the list above were my favorites. In my opinion, the best UV sterilizer that I highly recommend is the AA Aquarium Green Killing Machine. It serves its primary purpose effectively while also including some very useful features, like the indicator light for the UV bulb and a pre-filter.

Although this particular unit is suitable for tanks up to 50 gallons, you can purchase ones from the same brand with a higher capacity to fit larger aquariums. I went through lots of UV sterilizer reviews, and I found that I wasn’t alone: The AA Aquarium Green Killing Machine is highly recommended by other aquarists, too.

Your own choice of UV sterilizer units depends on your requirements and preferences. If you need an all-inclusive kit with an aquarium filter system, for example, I’d recommend a combination kit that includes a filter with a UV light, like the Sunsun Hw303B Pro Canister Filter Kit.

4. What To Consider When Choosing Your UV Sterilizer

Aquarists know that different tanks have different needs. Below are some considerations to take into account when choosing an aquarium UV sterilizer:

4.1 Tank Size

Each UV sterilizer is designed for a specific water volume capacity. Before purchasing, make sure the unit is compatible with the size of your fish tank. If the UV sterilizer has a lower capacity than the aquarium, it’ll take longer for algae to deplete and its overall efficacy will be hindered. The larger the tank, the higher the wattage of the aquarium UV sterilizer should be.

Tank size also determines the best aquarium UV sterilizer for your own setup; For example, for small fish tanks, HOB filters or internal sterilizers work well – Whereas for larger tanks or ponds, canister filters and in-line UV sterilizers should be considered. This is because larger tanks will need more advanced filtration and sterilization, which HOB filters and internal sterilizers are less able to provide for larger volumes of water.

4.2 Type Of Filtration System Available

Consider your filtration needs. If your fish tank already has an effective filtration system in place, you can simply get a UV sterilizer instead of a complete filter kit. But if you want a filter that includes an ultraviolet sterilizer, consider buying a canister filter or a HOB filter in a combination kit that includes the UV light. as well.

4.3 Type Of Aquarium


Reef tank


Some aquarium equipment isn’t designed for use in a saltwater or reef tank, as the components are not resistant to corrosion. This also applies to UV sterilizers, especially as they may include pumps and other parts which aren’t saltwater-friendly. This is why in the above UV sterilizer reviews, I mentioned the compatibility of each with freshwater and saltwater tanks. Be sure to review the product’s listing or packaging to verify its saltwater compatibility.

5. What To Look When For When Buying An UV Sterilizer For an Aquarium

Understanding the types of UV sterilizers out there and how they work can help you make an informed decision. Let’s take a look:

5.1 UV Sterilizer Dwell Time

The contact time between the tank water and the UV lights is referred to as dwell time. In simple terms, it means how long the aquarium water is exposed to the ultraviolet light of the sterilizer. The longer the dwell time is, the more effectively the water is sterilized.

By reducing the water flow rate, you can increase dwell time – But you can’t expect the water to be crystal clear and free of harmful bacteria by simply reducing the flow rate. This is because a low flow rate means that less tank water is circulated. As a result, it’s essential to determine the ideal water flow rate, which is often specified by the manufacturer of the aquarium UV sterilizer.

Here’s an example of how that might play out in your purchase decision: Let’s say the UV sterilizer you want to buy includes a built-in pump. In that case, it’s probably compatible with the ideal flow rate for the ultraviolet light bulb in the kit. But if you buy a UV sterilizer that doesn’t include a water pump, you have to make sure that it’s compatible with the one you have installed in your tank and with what your fish need. The ideal flow rate is specified by the manufacturer.

5.2 In-line UV Sterilizer

In-line UV sterilizers are one of the most popular types used in ponds and aquariums. This type of sterilizer uses a water pump to flow tank water through the UV chamber before flowing back into the aquarium. It’s an effective solution for most aquariums, but they typically don’t include a water pump, so if you’re buying one of these UV aquarium sterilizers, make sure to purchase a separate water pump that meets its required flow rate.

5.3 Water Flow Rates


Bubbles aeration flow


Water flow rates vary for different aquariums based on fish and tank needs. The flow rate affects the dwell time of the UV sterilizer, so the goal is to choose a flow rate that favors a good dwell time while achieving adequate circulation.

5.4 Turnover Rate

Turnover rate means the number of times water circulates through the UV sterilizers in a tank within an hour. A turnover rate between 1-1.5 is generally recommended to have a tank free of algae and other harmful parasites. For example, if you have a 100-gallon aquarium, a pump with a flow rate of 150 G/PH is what you’d go for.

5.5 Does It Use A Quartz Sleeve?

A quartz sleeve is the glass tubing that protects the UV bulb from moisture and potential damage from debris. Most UV sterilizers include a quartz sleeve, and I strongly recommend purchasing one with it. You can also buy one separately as needed, based on the unit’s model or dimensions.

5.6 Easy Installation

You probably noticed that in the reviews above, I mentioned whether or not the UV sterilizer was easy to put together. While some UV sterilizers are ready to operate, some require plumbing and complex assembly. If you’re a beginner with vague knowledge of the installation of this equipment, you might consider buying a UV sterilizer that’s easy to set up and includes instructions.

5.7 LED Control Box

I love UV sterilizers with an LED display on them. This option makes it convenient to control the UV light, but of course, it’s not mandatory. Personally, I go for this option whenever I can.

5.8 Warranty And Replacement Parts

Warranties are a huge deal, especially if you’re not buying from a well-known aquarium company. Most manufacturers offer a warranty period for factory defects of the UV sterilizer. I definitely recommend purchasing from a seller that offers a warranty because if the product doesn’t work, you don’t have to worry about losing your money! UV sterilizers can be pretty expensive, so it’s also a good idea to purchase from a brand that sells spare parts (such as the bulb). It’s worth doing research ahead of time to make sure that spare parts are readily available.

6. What Is A UV Sterilizer, And How Does It Work?

An aquarium UV sterilizer is an accessory that uses ultraviolet light to eliminate algae blooms, parasites, and other microorganisms in a fish tank. When the tank water is exposed to the UV rays of the sterilizer, the algae and other harmful microorganisms get depleted. A UV light has no effect on fish unless it’s directly placed in the tank. The UV light should always be kept away from sight as it could harm the fish’s eyes.

7. How To Install A UV Sterilizer

The exact method of installing a UV sterilizer depends on what kind you buy. Generally, internal UV sterilizers are attached to the interior walls of the fish tank using suction cups. Meanwhile, canister UV filters and external UV sterilizers are placed outside the water, and they use a pump to circulate water through them instead.

Whichever type of UV sterilizer you use, one of the main things to look out for is leaks! Make sure that any sockets or ‘O rings’ have been firmly fitted to prevent any forms of leaking.

Another tip is to attach the UV sterilizer after the filter, which means the filtered water will go through the light. This helps minimize the formation of dirt on the UV light, requiring less cleaning as a result.

8. Frequently Asked Questions

UV sterilization

UV sterilization has many applications outside of fishkeeping, from disinfecting medical parts to home cell phones.

8.1 How Often Should I Clean My UV Sterilizer?

A UV sterilizer isn’t something that requires frequent maintenance, like filters. Cleaning the UV light once every 6 months is usually adequate to maintain maximum UV effectiveness, but keep an eye on yours until you figure out how often you need to clean it. It may be shorter than 6 months.

8.2 How Often Should I Change The UV Bulb?

I usually replace the UV bulb every 12 months. If your UV sterilizer running times are limited, you may be able to use the bulb longer. There are also UV sterilizers that use a long-lasting UV bulb for clearing water; Manufacturers often specify the durability of such UV bulbs, so you’ll want to stick with what they recommend.

Another method is to run the aquarium UV sterilizer until you notice the slightest reduction in its effectiveness (eg, a bit of algae starts to spring up). This way, you’ll get maximum usage out of the bulb. Just know that your tank water may not be effectively sterilized during the end stages of the UV bulb.

8.3 How Long Should I Run My UV Sterilizer Each Day?

A UV water sterilizer needs to operate 24 hours a day for maximum effectiveness, but this can vary depending on the tank. For example, if your tank isn’t algae prone due to low exposure to sunlight, you can probably switch it off for a few hours to increase its durability.

8.4 Do Aquarium UV Sterilizers Require Maintenance?

Aquarium sterilizers require maintenance but not as regularly as filters. Simply rinsing the sleeve and the glass exterior of the bulb once every 4-6 months is usually sufficient.

8.5 Do UV sterilizers actually work for aquariums?

An aquarium UV sterilizer can do wonders in ponds and fish tanks. Unless you accidentally buy a fake UV sterilizer (they’re out there!), they tend to do a good job supplementing your regular tank maintenance and cleaning routines by knocking out algae, parasites, etc. If your aquarium setup or pond is visually disrupted by green water, having a UV sterilizer would be of great value. They’re also proven to kill bacteria that are harmful to fish while causing no harm to beneficial bacteria.

8.6 What Is The Best UV Sterilizer For a 75-Gallon Aquarium?

The Aquatop SP-7 UV aquarium UV sterilizer is a UV sterilizer designed explicitly for a 75-gallon aquarium. For a tank of this size, an internal UV sterilizer or a UV canister filter can be considered.

8.7 What Is The Best UV Sterilizer For a 10-Gallon Aquarium?

The Grech CBG Hang-On Back Filter With UV Light includes a UV sterilizer, which would be ideal for a 10-gallon aquarium. For nano tanks of this size, a HOB filter with UV is the best option, in my opinion.



To say that I’m obsessed with all things saltwater is a bit of an understatement. Aquarium Passion has served freshwater and saltwater aquarium hobbyists for over 10 years, and I'm committed to keeping the information accurate and free. My post-bac certification in Sustainability informs my writing about aquarium conservation efforts. When I'm not writing at AP, I'm out in the ocean or researching weird fish.


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