Best UV Sterilizer for Freshwater Aquarium – Top 6 Reviews, Guide, FAQs & More

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You’ll agree with us when we say that a lot of aquarists tend to overlook UV sterilizers but with the proper research and use, they really can do wonders for your freshwater aquarium. 

That’s why we decided to test out many popular UV sterilizers for freshwater aquariums in order to understand their potential and what their capabilities are. 

Today, we’ll discuss why you should get a UV sterilizer for your freshwater aquarium and what are some things you should look for in a well-constructed one. 

Top Pick

Coming with a streamlined, intuitive design, this product takes no time in being set up. Not only that, it also cleans freshwater aquariums much quicker than its competitors.

Runner Up

With a nifty 3-watt motor and a small footprint, this UV sterilizer is perfect for smaller freshwater aquariums. It doesn’t take up a lot of space and it’s incredibly powerful.

Also Great

This product comes with a filter pump attached in order to circulate the water through it. The pump itself is quite powerful but it works extremely quietly despite that.

We’ve conclusively found these three to have the most effective performance and ease of use out of all the UV sterilizers we tested. 

Now, let’s get into the reviews for the best UV sterilizers for freshwater aquariums.

Best UV Sterilizer for Freshwater Aquarium - Best 6 Reviews

1. Overall Best UV Sterilizer for Freshwater Aquariums - AA Aquarium Green Killing Machine Internal UV Sterilizer Review

This is a product that pretty much set the benchmark for us when we tested it of what every UV sterilizer should strive to be. Almost every test that we put this UV sterilizer through to test its different aspects from performance to ease of operation, it passed with flying colors. 

It comes with its own filtration pump so you don’t have to go out and buy one separately. The filtration pump is very powerful and adequate enough for aquariums as big as 50 gallons and despite being powerful and pumping water at an incredible rate, the pump makes little to no noise in your freshwater aquarium.

Features of AA Aquarium Green Killing Machine Internal UV Sterilizer – Best UV Sterilizer for Freshwater Aquarium

  1. Dimensions: 16 inches by 10 inches by 14 inches
  2. Weight: 1 pound
  3. Appropriate for aquariums up to 50 gallons
  4. Suction-cup mounting
  5. Operating capacity: 9 watts
  • Easy to install
  • Filtration pump included
  • Comes with a 3-year warranty
  • Lightweight for its size
  • LED indicator for UV bulb replacement
  • Body is made from fairly fragile plastic

If you’re looking for a dependable UV sterilizer for your freshwater aquarium, this is the product for you. It comes with everything you need and the 3-year warranty is really something that puts you at ease.

2. Best Small UV Sterilizer for Freshwater Aquariums - AA Aquarium 3 Watt Green Killing Machine Review

This is a smaller version of the product featured in entry #1. It pretty much contains all of the good aspects of entry #1 but in a smaller package. You can rest assured that this UV sterilizer will provide your small freshwater aquarium with powerful and effective sterilization without disturbing or annoying your fish in the slightest. 

Its small size also means it won’t take up too much space inside your aquarium and your fish will have ample space to swim around which is paramount for their health. 

Features of AA Aquarium 3 Watt Green Killing Machine

  1. Dimensions: 2 inches by 2.4 inches by 7.3 inches
  2. Weight: 6.5 ounces
  3. Appropriate for aquariums up to 20 gallons
  4. Filtration pump included
  5. Pump flow rate: 50 gallons per hour
  • Works silently 
  • Easy to mount onto aquarium
  • Easy to handle and use
  • Lightweight
  • Incredibly compact
  • Some reviews say that the unit tends to burn out within a couple of months

If you’re worried about a UV sterilizer taking up too much space inside your tank then this is the product you’re looking for. It’s small in size but its performance is powerful as ever. 

3. Best Underwater UV Sterilizer for Freshwater Aquariums - SunSun JUP-01 9W UV Sterilizer Submersible Filter Pump Review

This is a UV sterilizer that packs incredible performance into a small-sized UV sterilizer and it also comes with a very modest price tag. You’ll find that its high-speed filtration pump does a great job of circulating the water in a way that doesn’t cause too many strong currents inside your aquarium. 

The inside is designed in such a way so that the maximum possible amount of UV light hits the water and from many different angles so all the harmful microorganisms are killed off effectively. 

Features of SunSun JUP-01 9W UV Sterilizer Submersible Filter Pump

  1. Dimensions: 12 inches by 3.3 inches by 3.8 inches
  2. Weight: 2 pounds
  3. Appropriate for aquariums up to 75 gallons
  4. UV light operates at 9 watts
  5. Pump flow rate: 210 gallons per hour
  • Highly effective
  • Inexpensive
  • Lightweight for its size
  • Compact for its performance
  • Operates silently
  • Motor has a tendency to wear out rather quickly

If you want a well-designed UV sterilizer with a reasonable price tag then this product is definitely for you. It has a smart design and it’s easy to mount.

4. Best UV Sterilizer for Freshwater Aquariums with Adjustable Pump - Sun 13W UV Sterilizer Adjustable Pump Filter Review

A lot of UV sterilizers come with pumps that have no option of adjusting the flow rate at all. This can definitely be a problem as very rarely do you find a pump that has a flow rate that is absolutely compatible with the size and shape of your aquarium. In most cases, some adjustments are almost always needed. 

That’s where this product shines. Its adjustable flow rate feature makes it very easy for you to adjust it until the water circulates perfectly inside your freshwater aquarium. 

Features of Sun 13W UV Sterilizer Adjustable Pump Filter

  1. Dimensions: 3 inches by 2.5 inches by 13.5 inches 
  2. Weight: 2 pounds
  3. Suitable for aquariums up to 150 gallons
  4. 13-watt UV light
  5. Filtration pump included with an adjustable flow rate
  • Lightweight for its size
  • Doesn’t require a lot of maintenance
  • Easy to assemble and mount
  • Easy to use
  • Consistent performance
  • Comes with a built-in filter so you have no choice but to use that filter for your aquarium

If you’re worried you won’t be able to find a UV sterilizer with a pump that’s perfectly suited to your aquarium then this is the product you’re looking for. It’s beginner-friendly and is also easy to maintain.

5. Best Heavy-Duty UV Sterilizer for Freshwater Aquariums - Coralife Turbo-Twist UV Sterilizer Review

So far, we’ve been talking about UV sterilizers that most beginner fishkeepers or casual hobbyists would want in their small to medium-sized aquariums. This is a product that’s not aimed at them at all, it’s aimed at the big boys. The advanced aquarists that have extremely large aquariums to take care of. 

We put this heavy-duty UV sterilizer to the test by having it sterilize our largest freshwater aquarium which has a capacity of 450 gallons. It had murky water throughout it and many pockets of algae deposited in it. It was able to easily clean its waters up within 6 days.

Features of Coralife Turbo-Twist UV Sterilizer

  1. Dimensions: 20.9 inches by 3.9 inches by 5.6 inches
  2. Weight: 7.25 pounds
  3. Appropriate for aquariums up to 500 gallons
  4. Water pump included
  5. Water pump flow rate adjustable between 300 and 900 gallons per hour
  • Indicator light tells you when it’s operational
  • Twist design makes sure UV light effectively hits the water
  • Highly durable
  • Require little maintenance
  • Easy to use
  • Quite heavy and difficult to handle 
  • Quite expensive

If you’re looking for a UV sterilizer that can handle an extremely large aquarium, you’ve just found it. It’s small in size considering how powerful it is and it’s very well-built.

6. Best Easy Installation UV Sterilizer for Freshwater Aquariums - AquaTop In-Line UV Sterilizer Review

Many aquarists are turned off by too much equipment inside their aquariums. Most freshwater aquariums aren’t even that large in size usually and it really is an ugly sight when most of the inside is devoted to ugly aquarium equipment. That’s where this product comes in. It’s an in-line sterilizer that is placed outside your aquarium. 

Since it doesn’t take up any space inside your aquarium, you don’t have to worry about it crowding up your tank or disturbing your fish. 

As for its performance, it’s as impressive as any other entry on this list. It’s a product that can easily go head-to-head with any of the other products we’ve talked about so far. 

Features of AquaTop In-Line UV Sterilizer

  1. Dimensions: 12.8 inches by 2 inches by 2 inches 
  2. Weight: 1.75 pounds
  3. 10-watt UV bulb
  4. Pump included
  5. Pump flow rate: 211 gallons per hour
  • Does not take up space inside the tank
  • Easy to install
  • Easy to maintain
  • Highly sturdy
  • Effective performance
  • Not waterproof

If you don’t want too much clutter inside your freshwater aquarium then this product is ideal for you. It’s easy to get started with and it runs consistently for a long time.

best uv sterilizer for freshwater aquarium

Buyers’ Guide

What can a UV sterilizer do for my freshwater aquarium?

The biggest advantage of UV sterilizers is the fact that they use UV light to eliminate a whole assortment of bacteria, viruses and other harmful microorganisms inside your aquarium. This is the main reason why they’re ignored by many beginner aquarists; because their effect and benefit are not plain to see by the naked eye. 

UV light has a property where it restructures the cells of these microorganisms to the point where they can no longer function properly. This prevents them from harming your fish or aquarium plants and it also prevents them from multiplying. In this way, a UV sterilizer can help protect your fish from virus outbreaks, diseases as well as algae blooms. 

Do I really need a UV sterilizer for my freshwater aquarium? 

The truth is that not all freshwater aquariums really need a UV sterilizer. If you’re a beginner with a new, small aquarium setup, you may want to skip on getting a UV sterilizer initially. It’s not a piece of equipment that is absolutely essential in ensuring the successful running of a freshwater aquarium. 

That being said, we do encourage you to get a UV sterilizer installed in your freshwater aquarium if you have the money, time and space available. The benefits that a UV sterilizer provides your freshwater aquarium with really pay for themselves and you can rest easy with a UV sterilizer knowing that your aquarium will be free from all sorts of diseases and viruses in the future. 

How can I effectively choose the best possible UV sterilizer for my freshwater aquarium? 

Here are some aspects to look at when buying a UV sterilizer for your freshwater aquarium that can help you make the most appropriate choice: 

  • Flow Rate 

This has more to do with the air pump connected to the UV sterilizer than the UV sterilizer itself but it’s highly important that you get its flow rate right according to your aquarium’s size. Having a low flow rate will render your UV sterilizer useless while having too high a flow rate will cause too much disturbance inside your aquarium. A good rule of thumb is to have an air pump with a flow rate that is four times that of the size of your aquarium.  

  • UV Sterilizer Size 

The physical dimensions of your UV sterilizer actually matter a lot. This is because a lot of freshwater aquariums are quite small in size and already have a lot of aquarium equipment stuffed inside them such as a filter, a heater, etc. You need to judge how much space you have left inside your aquarium and get a UV sterilizer that doesn’t take up too much space so your fish have enough room to swim around. 

How do I set up my UV sterilizer for my freshwater aquarium?

UV sterilizers are fairly straightforward to set up since they come mostly pre-assembled. All you have to do is mount them onto your aquarium. If you have an external UV sterilizer, be sure to mount it between the outlet pipe of your filter and your aquarium so that the UV sterilizer is sterilizing the filtered water before it goes back into your aquarium. 

An important thing to note is that you should never set up your UV sterilizer during the process of cycling. A UV sterilizer will prevent the birth of beneficial nitrifying bacteria inside your freshwater aquarium so it’s very important that you cycle your aquarium first and then set up your UV sterilizer later. 

How do I use my UV sterilizer for my freshwater aquarium?

There’s really nothing to it when it comes to a UV sterilizer as it does most of the job for you. All you have to do is set it up properly and turn it on. The pump will start pumping water into the UV sterilizer and it’ll start working. That’s it. You’re done. 

Frequently Asked Questions (FAQs)

How much electricity does a UV sterilizer normally consume?

This can vary highly depending on how powerful your UV sterilizer is and how big of an aquarium you need it for. Most common-sized UV sterilizers usually work within the 3-watt to 12-watt range. 

If you have a pond or an extremely large aquarium for which you’ve employed a UV sterilizer, those kinds of heavy-duty UV sterilizers can go up to 36 watts. 

Can my UV sterilizer cause stress-related diseases in my fish? 

Instances of stress-related diseases have never really been found in aquarium fish due to a UV sterilizer specifically. However, you should definitely be wary about how long you let your UV sterilizer run inside your freshwater aquarium. Excessive shining of UV light inside your freshwater aquarium may not cause stress-related diseases in your fish but it can definitely cause other problems for them which could be catastrophic and irreversible such as retinal damage. 

How long should I keep my UV sterilizer on? 

This can vary by a lot depending on how powerful your UV sterilizer is, how big your freshwater aquarium is and how dirty it is. 

When you first set up your UV sterilizer, it’s recommended that you let it run continuously for at least 24 hours if your aquarium is relatively clear. On the other hand, if your aquarium is infested with algae or has cloudy water, then it’s recommended that you let your UV sterilizer run continuously for many days until the water becomes clear. Note that this running should be accompanied by regular water changes to get rid of the dead algae. That’s the only way the water will become clear. 

For a regular aquarium that is relatively clean and has had the UV sterilizer running on it for a while now, you usually let it run for an average of anywhere between 8 to 12 hours a day. 

How long does it take for a UV sterilizer to sterilize a freshwater aquarium? 

Again, there are a lot of factors that can affect how long a UV sterilizer will take to sterilize your freshwater aquarium. If your aquarium is relatively clean, you can expect the UV sterilizer to have it completely sterilized within 1 – 3 days. If you have a large aquarium and it’s infested with algae and has murky water, etc., then you should expect the UV sterilizer to take at least 5 – 10 days before your aquarium is properly sterilized. 

Can a UV sterilizer harm my freshwater aquarium plants?

No. You don’t really have to worry about UV light harming your freshwater aquarium plants. It has no effect on them.

Can a UV Light cause algae problems?

No. On the contrary, algae is one of the main reasons why many aquarists invest in a UV sterilizer in the first place. UV light works by breaking down the cell walls of algae cells. As a result, these tiny cells clump together in the form of dead cells which can then be easily removed through your aquarium filter’s mechanical filtration system or manually by you through regular water changes. 

Is a UV sterilizer an essential piece of aquarium equipment? 

It’s not essential in the sense that you don’t need it in your aquarium to successfully run it initially like you would, say, a filter or a heater.

How can I determine how big of a UV sterilizer I need? 

We’ve discussed how you can determine the flow rate of the UV sterilizer’s pump above (it should be at least four times that of your aquarium’s size). In the case of the wattage, most UV sterilizers have a wattage of 9 watts which is appropriate for freshwater aquariums in the 50-gallon to 75-gallon range. Smaller UV sterilizers usually have a wattage of 3 watts and are appropriate for aquariums around 20 gallons. As for larger UV sterilizers meant for ponds and large aquariums, they can have a wattage of up to 36 watts. 

My UV sterilizer doesn’t seem to be having any apparent effect on my freshwater aquarium. Why is this? 

Sometimes, a UV sterilizer takes time to show its effect. Firstly, have some patience and let your UV sterilizer run for at least a few days. If it’s been a few days and your sterilizer still hasn’t been able to fix your aquarium’s problems, then you should check to see if all of its wiring is properly connected or not. Also, check to see if anything’s damaged or broken. If you fail to find anything wrong, one last thing you can try is replacing your UV bulb. If that doesn’t fix things then we recommend you contact the manufacturer for a replacement. 

Can a UV sterilizer cause my freshwater aquarium’s water temperature to increase?

The UV bulb in a UV sterilizer definitely does put out a small amount of Infrared but this amount is not high enough to cause any significant change in the temperature inside your aquarium. If your UV sterilizer is causing your aquarium’s temperature to increase by a drastic amount, that means there must be something faulty inside it and you should get it checked. 

Final Verdict

UV sterilizers can be a powerful tool that can really help keep your aquarium’s environment clean and free from diseases when used correctly. 

After months of speculation and testing, we’ve concluded that the AA Aquarium Green Killing Machine Internal UV Sterilizer is the best UV sterilizer for freshwater aquariums. It shows its effects very quickly, it’s very powerful, it’s incredibly quiet and it’s not that expensive either. 

And this brings us to the end of our post for the best UV sterilizers for freshwater aquariums. 

Give us feedback and let us know what UV sterilizer you’re using for your freshwater aquarium.

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