Should You Use a UV Sterilizer in Your Fish Aquarium

By Jecinta Muturi @aquariawise

Should You Use a UV Sterilizer in Your Fish Aquarium

Controlling microorganisms such as bacteria, viruses, and algae in a closed environment such as the one in your fish tank can be quite challenging. As such, it helps to have a way to keep pathogens at bay…

…I mean, prevention is always better than cure, yes😃?

An aquarium UV sterilizer is one such item. It stops the spread of organisms and parasites inside a fish tank; from one fish to the other and from the ecosystem to your aquatic life.

Essentially, a UV sterilizer is a tube of ultraviolet light that kills single-cell organisms that go through it by altering and damaging their DNA. the aquarium guide

A UV light should kill most of the microorganisms in any water that flows to the sterilizer with no residual effect to your fish.

That said, a UV sterilizer in a fish tank is not a must, but it is highly recommended both in freshwater and marine aquariums to effectively keep your fishes safe.

So, should you get a UV sterilizer for your aquarium, well, yes, if you need to keep your tank in pristine condition. But if you can manage to keep your aquarium CLEAR and HEALTHY without much trouble, it is quite ok to operate it without one.

Please read on for more insight.

What Does A UV Sterilizer Do in A Fish Tank

As I mentioned above rather briefly, a UV sterilizer is used to kill and eliminate any disease-causing microorganisms and parasites, and ensure your aquatic life remain safe and healthy at all times.

Aquarium UV sterilizers eliminate cloudiness, algae, bacteria, and other odd-elements to give your fish the crystal clear water they need for perfect health.

UV lights can be used either in a reef, marine, or even freshwater (tropical) aquariums without harming coral, fish, inverts or plants in the tank.

Quite often, UV lights are also recommended when dealing with cloudy water and want to improve your tank clarity, and also for fish tanks with algae overgrowth, that cause green aquarium cloudiness.

As such, if cloudy-murky water, algae bloom, or persistent diseases plague your fish tank, consider combating the problem with a UV sterilizer.

Most products are well priced and are available in most chain pet stores, though you can also get our recommended unit: AA Aquarium green killing machine on Amazon. Please note the unit is rated for specific tanks sizes, so be sure to get the best size for your aquarium.

Plus consider purchasing the unit together with this spare bulb for better convinience.

How Do Aquarium UV Sterilizers Work

Aquarium UV sterilizers use a fluorescent lamp that produces light within the ultraviolent wavelength (250 nanometers).

This light radiates any water that passes over the bulb, and restructure the DNA of all single-celled organism within the column, such as bacteria, keeping them from multiplying and your aquarium safe.

Essentially, the radiation should be able to kill most viruses, bacteria, algae, and protozoan, though a higher dosage of UV is required to expel large organisms than smaller ones.

The capacity of a UV sterilizer is mostly dictated by the strength of the bulb, meaning a lamp with more wattage is able to produce better results.

Keep the bulb clean and replace it on a regular basis since old or dirty UVs with weak lamps don’t do much at all.

Anywhere from 6 to 12 months is about the length of time most UVs bulbs last, though premium products can get to the 14 months mark.

Optimal temperature (104°F to 110°F) is also crucial for best results. So to keep your bulb from low heat settings occasioned by the cooler tank water by adding quarts sleeves around the bulb.

A few other things you might want to consider when getting a UV sterilizer is the light penetration and contact time.

That said, note that your water turbidity plays a crucial part in the light penetration, as such, place your UV sterilizer after your filter where the water is as clear as possible when it enters the unit.

Regarding contact time, just know that the amount of time the water stays in the UV sterilizer, the more effective the process will be. For the best result, slow your water flow rate to increase the dwell time and contact with the light.

Most UV lights will work in most aquarium setup as long as they are with the rate size, even so, the results tend to be more apparent on smaller tanks than in big aquariums.

Please note that UV sterilizer will not kill your aquatic life, but it will also not save fish that are already battling an infection. Therefore, make sure you treat any ill animals in your setup even when you add the light.

Lastly, when installing your UV light, make sure you follow the instructions on the unit manual and protect yourself always.

You may want to use gloves when touching the lights and wear eye protection. Plus its also a good practice to keep the light unplugged until you have installed it.

How Long Should UV Sterilizer Be on in an Aquarium

How long your UV sterilizer stays on will depend on the challenge you are facing, but I recommend you start by running it 24/7 until your water clears and continue for another week or two.

Couple that with ample water- changes to remove any dead organisms in the cleaned water such as algae.

After this initial period, it perfectly Ok to run it as needed depending on your tank conditions. You can even choose to use a timer stripe to bring your UV online with your aquarium lights and shut off when they go out.

That said, with time you’ll discover smaller UV sterilizers are not as powerful and may need to be run longer for them to be effective. Luckily, they also do not produce enough power to hurt anything, so you need not worry about running them too much.

One other reason you may want to have your UVs longer is the bulb life, which is substantially decreased by running a unit on and off all the time; most are designed to remain on all the time.

Do UV Sterilizers Kill Ich

Most if not all hobby grade UVs do a better job at killing algae and bacteria bloom and clarifying your water than parasite control.

As such, aquarium UV lights are not the most effective solution to ich, especially when on a fish body, though you may get desirable results when the parasites are in the free-swimming stage.

UVs sized in general to kill waterborne bacteria, viruses, and algae might not be strong enough to have a significant impact on ich.

If you intend on adding a UV sterilizer in your tank to solve an ich problem, I then recommend implementing it with other approaches for better results. Alone, the light can only be ideal for brief uses only.

Raise the temperature in your fish tank and add aquarium salt accordingly while you run the UV sterilizer to target ich.

Myself, I Increase the temperature in the aquarium to between 86 and 90 Fahrenheit and add salt (ratio 1 table-spoon per 5 gallons) for 10 days straight.

Alternatively, quarantine your fish and use liquid ich medicines like API liquid ick or powder formulars like this super ick cure powder.

Please note that you may also need to add medicated food to garlic guard to entice your finicky fish into feeding to get cured.

Once your sick fish are settled in quarantine, then you add your UV sterilizer in the main tank to eliminate any parasites that might be still lingering in the water column.

Do UV Sterilizers Kill Algae

Another somewhat common question about what an aquarium UV will do or not do is if it will kill algae.

And unsettling as it may be, it does depend.

A UV sterilizer will kill free-floating algae cells when the water is passed through the unit and reduce the build-up rate. But it will not kill any algae stuck on decorations and rocks or the dusting that comes up on aquarium glass quite often.

For this kind of algae, you would need to manually remove them with an algae scraper (scrubber pad) or razor blade.

For the best results, use your scraper/razor at 45 degrees to scrape your aquarium glass, at least twice a month, more so when doing your monthly cleaning.

Also keep up with your weekly water changes and use the UV sterilizer to expel any green water that ensues as a result of algae residue falling in the water and any kind bloom.

Having said that, depending on the size of your UV and flow, your unit might be able to kill all kinds of algae.

Reducing factors that help algae thrive, such as long light-on hours and excess nutrients, will help you combat it more readily as well.

Where To Put UV Light (Sterilizer) in Aquarium

The way to put a UV sterilizer in a fish tank depends on the design, but submersible units (the most common type), function optimally when placed at an angle, vertically or horizontally in your aquarium or sump.

Because turbidity affects the efficacy of the light, you also want to place it behind an air pump or filter flow path. This will ensure the water is clear while it gets inside the unit.

Moreover, please note that some UVs units go inline with your filter unit (canister), while others go inside the tank. As such, the placement of each will be uniquely optimal at different settings.

Be sure to expose your UV sterilizer to a unique flow of water that ensure there is maximum contact with the light.

If there is any way your UV light won’t penetrate the water, you may also want to resolve that. Otherwise, it becomes ineffective to have it in the first place.

Best Aquarium UV Sterilizer

Well, all aquarium UVs function a lot like fish tank filters

…though while filters draw in water, pass it through mechanical and biological cleaning, and then release back to the tank, microorganisms still survive.

Aquarium sterilizers instead kill off the free-floating microorganisms by exposing them to a lethal dose of radiation while still functioning similarly by drawing in and releasing aquarium water.

As such, the best UV sterilizer is the unit that best gets the job done, that is, kill the most microorganisms, and be appropriate for your fish tank.

Below are the units that we recommend and are available on Amazon.

1—AA Aquarium Green Killing Machine Internal UV Sterilizer

The AA aquarim green killing machine is one of our top recommended product.

It’s particularly ideal when dealing with aquarium clarity issues, including green water caused by algae bloom. The product comes in several sizes including this one, each ideal for different setups.

This UV light rays are effective in controlling free-flowing bacteria, yeast, mold, and other pathogens, and cleaning up green water or cloudiness without any need to use chemical.

You only need to make sure you purchase a sterilizer that is large enough for your aquarium.

That said, a few challenges you may experience while operating an AA aquarium green killing machine is changing the bulb.

First, the bulb is self-contained and cannot be replaced on its own. Instead, you have to change the entire casing, lamp, and wires.

Plus it is a proprietary setup, so you cannot buy a replacement from anywhere, you need to get an exact bulb for it.

For that reason, I recommend you purchase a spare lamp together with the sterilizer or order it sometime before the bulb fails and have to be replaced.

There is also slight talk about the product being cheaply built thus having a short lifetime, but from our own due diligence, we believe its an all-around great product.

2—Sun Jup Aquarium in Tank UV Sterilizer

By far the biggest pro of the Sun Jup UV Sterilizer we’ve seen its ability to reduce algae, though it also quite effective at keeping the water clear, albeit at lesser efficacy than that of the green killing machine.

As far as disease management goes, this UV light has pretty modest efficacy, though nothing too extraordinary. As such, couple it with other remedies if fighting pathogens in your fish tank.

One more thing we liked about this unit is that it came with a spare bulb on the initial purchase (from the linked seller) meaning its spares the buyer the headache of getting another lamp for a decently long minute.

3—Corallife Turbo UV Sterilizer

This sterilizer has exceptional water cleaning capacity. From experience, it will deal with any coloration in your tank in a matter of hours.

It is also an all-around versatile UV, usable both in freshwater and marine aquariums.

It features a spiral-helix water path with the design able to increase the exposure time of water to the UV rays, maximizing the destruction of algae cells, parasites, viruses, and bacteria pathogens.

You can position it under your aquarium or mount it at the tip of the tank. As much, the 9-foot power cable is another feature you’ll appreciate.

The bulb should last about one year before you need to change it, and is easy to replace.

Lastly, the Corallife turbo twist sterilizer is rated for aquariums up to 250 gallons, which is quite impressive considering most aquarium UV lights are only efficient in small-size tanks.

That all for this post, for more insight, tips, and hacks, follow Aquariwise on Facebook or Instagram.

Happy fish keeping.

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