If you’ve ever had a mysterious breakout of some kind among your fish, you may be wondering what you can do to prevent it in the future.
There are things you can add to the aquarium system that can help – having the right filtration is the first step, setting up a fish tank with live sand and live rock helps, as well – but what if the basics aren’t doing it?
Enter the best UV sterilizer, a device designed specifically to kill of nasty the little microorganisms you can’t see in your aquarium water, although they may show up via cloudy water.
Best UV Sterilizer Quick-Find Table
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What is a UV Sterilizer?
Simply put, a UV – or Ultraviolet – sterilizer is used to control infections by stopping the spread of unhealthy microorganisms from one fish to a coral or invertebrate or other fish.
This spread happens through the water – much like infections happen through the air for humans and mammals – as well as via things like free-floating algae.
When used correctly, these UV sterilizers kill off the microorganisms before they can spread. These bad guys have to be in the water, though for the sterilizer to work. The UV light will not kill organisms attached to fish or corals – they must be free-floating.
How do UV Sterilizers Work?
UV tank sterilizers use a germicide fluorescent lamp that creates light at a wavelength that irritates and kills of algae.
The water and algae pass over the bulb – or around it, if a quartz sleeve is used – and is irradiated by the wavelength of light.
The light penetrates the algae and bacteria, and as it does so, the DNA mutates and prevents the growth and multiplication of said nasty organisms.
What Factors Influence the Effectiveness of UV Sterilizers?
There are several things that affect the effectiveness of an aquarium UV light.
Type and Size of the Organisms
First, the size and type of organism can determine whether or not the UV sterilizer for fish tanks will work.
Ultraviolet light can kill viruses, algae, bacteria, and protozoa, but some require much higher doses to do them in. Plus, some bacteria are more resistant to UV radiation than others.
The power of the UV bulb also has a significant affect on how powerful the affects will be on those nasty killers in your aquarium. The wattage of the bulb will tell you the amount of UV light that’s created by the bulb.
Bulbs with higher wattage create more UV light, and the ability of the germicidal fluorescent bulbs to produce the light decreases with age over time. In most cases, you need to replace the bulb about twice a year.
UV light is also produced by higher temperatures – between 104 and 110-degrees Fahrenheit – while cooler lights will produce less UV radiation.
Penetration of the UV Light
If the UV light can’t penetrate the water, it won’t be able to kill off the algae and organisms. High water turbidity decreases penetration. You should place the ultraviolet aquarium filters after the biological and mechanical filter media within your filtration system so that the water is cleared by the time it reaches the UV bulb.
Also, salinity affects the effectiveness of UV light on the organisms. UV light penetrates freshwater better than it does saltwater.
Finally, the cleanliness of the sleeve or bulb also affects this power of the UV. If there’s a salt deposit or film on the bulb or sleeve, the light won’t penetrate as fully and won’t be able to irradiate the bacteria.
Finally, the amount of time the UV light has to work on the bacteria makes an impact on its power. The more time, the more bacteria killing power you’ve got.
Contact time is changed drastically by the flow rate of the water in your aquarium.
While you’re treating the aquarium for such issues, you should probably consider reducing the water flow rates to help increase the contact time the UV filter has with the water.
Why Would You Need a UV Sterilizer?
Since the cleanliness of the aquarium has a huge impact on how healthy your aquarium is, the UV sterilizer is a potentially vital part of your system.
UV sterilization is a safer way to kill of bacteria, algae, protozoa, et cetera than some other methods, because it won’t kill your fish. For us, that’s obviously a huge deal.
So, if you’re seeing some unhealthy outbreaks in your tank, you definitely should consider using a UV sterilizer to help those fish, corals, and other critters out.
Drawbacks of UV Sterilizers
UV radiation is an effective killer for bacteria and other microorganisms, but there are some potential drawbacks.
UV Sterilizers Only Work in Clear Water
First off, UV light is only effective in clear water. If your tank is mucked with visible algae and murky water, you’re going to need to clean the water accordingly. Sometimes, this will clear up on its own, and sometimes it won’t. There are ways to treat this with a little time.
But since the fish tank water must be clear for the UV filter to work, you need to deal with that before beginning UV treatment.
UV Light Works in Tandem with Other Filtration But Not By Itself
UV lights work in tandem with other filters but does not replace them. UV cannot remove contaminants like copper or lead.
Other filter media must be used for this – or an RO system – which means UV lights add to your cost of the base for your little aquarium ecosystem.
UV Light Systems Need Electricity
You’re already powering multiple other devices to keep your aquarium running. The water pump, air stones, filter, LED light system, and various other devices that you may or may not opt for are already adding a bit to the energy bill. Adding on another device that uses some power increases that.
Most are designed to run efficiently, but they still do add some energy use.
How to Choose the Best UV Sterilizer Aquarium System
There are a few things you’ll want to do before making a purchase on a UV sterilizer.
Do Your Research
First you need to do your research. Learn about UV sterilization, how affective they are for situations in fish tanks like your own, and whether or not there are any suited to your specific needs. Be sure to read loads of UV sterilizer reviews to verify each one actually lives up the claims made – real-life users tell it like it is, usually, and tend to keep you up-to-date on any bad batches going out at the moment.
Consider Your Tank Size
UV sterilizers come in specific sizes to match specific fish tank sizes and flow rates. Learn which ones are suitable for the gallons of water in your fish tank you have.
Determine Which Type of UV Sterilizer Would Work Best in Your Setup
Much like filters, there are both in-line UV sterilizers and HOB – hang on back – options that may or may not suit your needs, depending on your exact situation. There are also submersible options which may also be the best choice for your aquarium, depending on aesthetics, size, placement, et cetera.
Keep your aquarium shape and aquascape in mind as you consider.
HOB sterilizers and submersible sterilizers are usually small and convenient – easy to install – while in-line sterilizers tend to be larger and more powerful.
Reviews of the Best UV Sterilizers For Freshwater and Saltwater Aquariums
As we dug through the many options for the best submersible UV sterilizer and the best UV sterilizer for reef tanks (among all the other options!), we found quite a number of choices to consider.
We looked through each with you in mind, using these criteria to determine which ones are actually effective – and not just paying someone advertising fees to a high-rating – and which ones are suitable for different types of aquarium settings. We looked for the following things in each product:
- High-quality materials and manufacturing process
- Well-trusted brands in the industry
- High review ratings from real-life aquarist hobbyists
- Effectiveness in doing the job – i.e. they actually do kill off the bacteria you’re trying to get rid of
- Ease of use
- Ease of installation and maintenance
The Advantage Series Aqua UV HOB Sterilizer is the best overall choice in UV sterilizers for aquariums. It’s a lightweight, hang-on-the-back unit that installs easily, quickly, and conveniently.
It’s effective at quickly sterilizing the water and killing off the green water caused by algae and the other crud that gets in there, and it’s easy to use and maintain over time.
- Type of UV sterilizer: HOB
- Tank size: Up to 85 gallons
- Best for: Freshwater aquariums
What We Loved
The UV sterilizer from the Advantage Series Aqua is a really great little machine. It mounts easily and quickly on the back of your aquarium. It’s slim and lightweight so it’s non-invasive and doesn’t effect the aesthetics of your fish tank much – if at all.
It’s easy to connect up the sterilizer, simply by connecting into the return line or pump. That makes this a really fantastic option for anyone, especially beginner hobbyists just learning how to use all of the various types of equipment in aquariums.
The 15-watt bulb is pretty powerful and really does the trick. Many folks have noticed a dramatic difference in their aquariums within just three to five days, thanks to this little beauty and the power of the bulb.
It’s best used for small and medium sized aquariums, up to 85-gallons in size.
Plus, we love that this is an American made product, so we know it’s high-quality and not some chintzy hunk of chunk chucked out of some factory overseas where quality control isn’t as important.
What We Didn’t Love
There is really only one issue we have with this UV sterilizer: the bulb doesn’t last a super long time.
It has to be changed semi-frequently – every 4 or 5 months, depending – and that can be a little tiresome.
Otherwise, it’s great! Just don’t use in a saltwater tank. It’s designed for freshwater aquariums.
Our Verdict on the Advantage Series Aqua UV HOB Sterilizer
Overall, the Advantage Series Aqua UV HOB sterilizer is a great, simple product. It does what it’s supposed to, and it does it well. It works quickly, quietly, and helps clear up the gunk pretty fast. Be sure to only use it in freshwater tanks, though, and check the bulb every couple of months to make sure it’s still working.
The AA Aquarium Green Killing Machine Internal Sterilizer with Powerhead is a great two-in-one device that really packs a punch to your aquarium ecosystem that’s been infected by algae and other microbes. It uses the powerful 9-watt bulb to sterilize and the powerhead to create a zig-zag flow pattern while increasing contact time to knock out the algae quickly and effectively.
- Type of UV sterilizer: HOB
- Tank size: Up to 50 gallons
- Best for: Small freshwater aquariums
- Bonus features: LED light control box with bulb indicators
What We LoveD
There’s lots to love about this little HOB UV sterilizer from AA Aquarium.
First, this little device packs a punch of unique algae killing power with a combination of UV light and powerhead used to create a zigzag pattern that increases water flow and contact time at the same time.
It’s also got a great LED light control box with bulb indicators that lets you know when you need to change out the bulb for premium effectiveness – i.e. before the bulb goes totally dead.
It’s also a sealed UV bulb, a unique feature, that’s designed to make changing the bulb as simple as possible. You don’t need any gloves, since you never touch the bulb, and it comes out easily and quickly.
The unit is also extremely easy to install, since it’s a HOB UV sterilizer. It comes pre-assembled, too, so it really just takes a couple of minutes to get in place. And we love that! Easy is always better.
What We DIDn’t Love
The only potential issue we see with this UV sterilizer is that the plastic it’s made with isn’t as high-quality as we’d like. It’s not utter junk, but it’s not as top-notch as some others – this is the reason it’s not number one on the list.
We like durable products that you don’t need to be delicate with. This isn’t crazy, but it’s also not the best because of that.
Our Verdict on the AA Aquarium Green Killing Machine
If you can handle the UV sterilizer from AA Aquarium with care, you’ll find this is the top of the line for getting rid of that nasty algae and those microbes that make your fish sick.
It’s got some great features like bulb indicators that tell you when to change them and a powerhead that creates a zigzag water flow pattern for increased contact time. It’s also easy to install and maintain. The only downside is the plastic isn’t the most durable out there.
The SunSun JUP-01 Submersible UV Sterilizer Filter Pump is a great option, especially for saltwater fish keepers with small aquariums. It does the trick in getting rid of the free-floating bacteria in there, and does it all without tubing or an additional circulation pump.
- Type of UV sterilizer: Submersible
- Tank size: Up to 75 gallons
- Best for: Small saltwater & freshwater aquariums
- Bonus features: Comes with a built-in pump
What We Loved
The SunSun JUP-01 is a fantastic option that has so many great positives that it’s definitely a top-three. For starters, it comes with a built-in water pump, so you don’t have to get a pump, too, in your aquarium. This saves time and energy, as long as you use it all properly.
Secondly, you don’t need any extra hardware to setup the system and keep it running.
It’s easy to mount the UV sterilizer with the suction cups that come with it – and they actually work – and that’s it. Mount and go. And you can either mount it horizontally or vertically, depending on which is going to be the least invasive for your aesthetics and setup.
And finally, and potentially most importantly, this UV sterilizer, when used properly, actually works for saltwater aquariums.
What We Didn’t Love
There are two things that we don’t necessarily love about this one.
The first is that it’s not designed for large tanks. This isn’t too big of a deal, except that because it’s the best UV sterilizer for saltwater tanks, that’s a little frustrating for those with marine tanks larger than 75-gallons.
The second is more problematic, but still workable. Several people we talked to reported that the motor burns out after prolonged use. The solution for this is doing what others have tried: running it initially to clear everything up, then only using it a couple times a week to maintain a clear, healthy tank.
Our Verdict on the SunSun JUP-01 Submersible UV Sterilizer Filter Pump
If you’ve got a saltwater aquarium, this is the UV sterilizer for you. It’s easy to mount, easy to maintain, and comes with its own water pump to help direct the water easily through the UV filter for the best contact time and cleaning action.
Just be sure to run it steadily upon installation to remove any outbreaks of microbes and bacteria, and then run it infrequently – say twice a week – to preserve the motor from burnout from over-use.
Anyone who’s owned a pond has probably heard of the brand Jebao. They’re one of the top leaders in the industry, creating high-quality pumps and UV sterilizers and other devices that power, clean, and clear a pond or large aquarium without problem.
The PU-13 Ultraviolet Clarifier is no exception to their rule of excellence. It’s durably built and suitable for both indoor and outdoor use. It’s got a special bulb chamber for maximum contact time, and it can handle extremely large volumes of water – up to 2000 gallons.
- Type of UV sterilizer: Inline UV sterilizer aquarium or pond
- Tank size: Up to 2000 gallons
- Best for: Large aquariums and ponds – freshwater or saltwater
What We Loved
If you’re looking for a powerful UV sterilizer that will work in an aquarium larger than 200 gallons, then you’re in luck. The Jebao PU-13 is a fantastic one that we love recommending to folks with large aquariums. It’s powerful enough to actually work with anything up to 2000 gallons.
And at that volume and power, it’s really a fantastic value and a “steal” at the price for such a powerful device.
It’s also an external/in-line aquarium UV sterilizer, so it doesn’t mess with the internal aesthetics of your beautiful aquarium.
We also love the unique bulb chamber that’s designed to give the water the most contact time with the bulb to clear away as much bacteria and other microorganisms as possible.
Finally, this sucker is built to last. It’s designed for both indoor and outdoor use, so it can handle pretty much anything you can throw at it.
What We Didn’t Love
There are really only two things we’re not in love with here.
The first is that though it’s an in-line UV sterilizer, it’s rather bulky and won’t work with smaller sumps. Presumably, if you’ve got an aquarium that holds more than 200 gallons, though, your sump should be able to handle it.
The second is that the instructions that come with it are incredibly useless. They’re simple, but don’t really help at all with figuring things out. If you do need help, you should check out some videos online for assistance instead.
Our Verdict on the Jebao PU-13 Ultraviolet Clarifier
The Jebao PU-13 Ultraviolet Clarifier is truly a fantastic option for anyone with a large aquarium. If you’ve got anything over 200 gallons, this is your best bet for successful UV treatments. It works on tanks up to 2000 gallons and is an external or in-line setup that doesn’t mess with your aesthetics.
It’s easy to use, incredibly durable, and really kicks bacteria butt. The only real issue is that it’s kind of bulky. For small setups, it won’t work so well.
Runners Up in Freshwater UV Sterilizers
Two other UV sterilizers worth mentioning include the SunSun 13 Watt UV Sterilizer with Adjustable Pump Filter and the Coralife Turbo Twist UV Sterilizer. Both are great for freshwater aquariums, though didn’t quite make our top list.
The SunSun 13W works for 150-gallon tanks with its powerful 13 watt power keeping it running. The pump works with 8 watts of power.
The combination helps to keep the water contact longer while giving you an adjustable water flow.
It can be used with either freshwater or saltwater, but I’d generally just recommend for freshwater tanks or mid-sized saltwater aquariums only.
The potential issue is that it’s made from less than high-quality plastic, so it can be a little delicate.
The Coralife Turbo Twist works for tanks up to 250-gallons.
It has a nice little indicator light that lets you know when the bulb needs changing and works for either in-line or hang on applications.
It uses a twist-flow design, which is also great, as that increases the contact time over most others and creates a nice, natural water flow for your fish and plants.