Best UV Sterilizer for Reef Tanks

You are caring for your marine aquarium matters a lot, ensuring its longevity and making sure that your fish are in good condition. While some might think that biological or mechanical means of filtration are enough, it is also essential to consider Ultraviolet (UV) sterilizers in maintaining the condition of your reef tank.

The best UV sterilizers for reef tanks are helpful in aquariums, small ponds, and other water features. It can clear water quickly and effectively. In this article, you will discover several benefits of using UV sterilizers and the reviews of our top picks to help you make an informed decision when you’re you’re ready to purchase one.

Benefits of a UV Sterilizer for Reef Tanks

It would be necessary first to know what UV sterilizers are. What do these devices do, and how does it work? A UV sterilizer could help stop the spreading of different microorganisms passed on through the water from one fish or coral to another. Controlling free-floating algae is also one important attribute of UV sterilizers. UV light could kill microorganisms that are free-floating (if it is operated correctly).

How does it work? First, this device uses a germicidal fluorescent lamp to produce light with a wavelength of around 2537 Angstroms equivalent to 254 nanometers. When water that contains the bacteria passes over the bulb, the wavelength irradiates it. The mutation of DNA of the bacteria that is affected by light penetration would prevent their growth or multiplication.

To which could we use UV Sterilizers, and what would be the benefits of having one? While UV Sterilizers generally work in an aquarium, their use in aquariums less than 24 gallons may not be practical. Multiple tank systems sharing standard filters would find UV sterilizers most helpful in controlling diseases which usually occurs when new fish species are introduced to an already existing aquarium set-up. This is typically the case since most hobbyists fail to use quarantine aquariums when adding new fish species.

Things to consider in buying UV Sterilizers

Knowing what to consider in buying UV sterilizers for your fish tanks is understanding the factors that could influence how effective a UV sterilizer works.

Organism’s type and size

Some of those that a UV sterilizer could kill are bacteria, algae, protozoa, and viruses, with each size and type requiring a different dose of UV radiation. For example, since protozoa are relatively larger, they require higher amounts than smaller organisms like bacteria. However, within the same organism, different types could exist that need additional doses since some types may be more resistant than others.

UV sterilizers usually have this killing dose: for Algae, 22,000 – 30,000; for Protozoa, 90,000, and Viruses, 15,000

Bulb Power

The wattage of a bulb defines the amount of UV light that it could produce. Higher wattage would mean more UV light to be produced. However, over time, a bulb’s capacity to produce UV light might decrease. This is why it is recommended that bulbs are replaced every six months. Temperature also matters in the production of UV light. At around 104-110 degrees Fahrenheit, UV light is produced best compared to cooler temperatures.

Penetration of UV light

UV light must penetrate the water. Penetration, however, is scarce when water turbidity is high. You would want clearer water so that UV light could penetrate it more. If the salinity of the water is high, penetration would also be difficult, which means freshwater could allow more penetration. UV sterilizers would be more effective in these types of water. You also need to make sure that nothing is covering the lamp of your UV sterilizer, for it may block the light.

Length of Contact Time

Generally, the longer the water is exposed to UV light, the killing power increases. What influences contact time is the rate of water flow. If water flows slowly, contact time is increased. Bub length also matters when it comes to contact time since UV light is in contact with the water for a longer time when bulb length is longer.

Now, here are several tips that are worth considering in buying your UV sterilizer:

  1. Choosing low-pressure UV lamps. These are the best match for aquatic UV sterilizers. Because they have low input power, you could use less electricity, helping you save money for the electric bill. Their useful life span is usually from 8,000 to 12,000 hours, which is sustainable enough. Their length would also allow for more contact time with water, making it more effective in cleaning your aquarium.
  2. Choosing UV sterilizers of body diameter 3 or 5 inches. It is important to take into consideration your UV sterilizer design as it affects its dose rate. A larger diameter means larger contact time, but you also do not want the body to be too large or small. The wattage of your UV sterilizer could also dictate the ideal diameter body it should have. For instance, when a low-pressure lamp has a wattage of 25, 3 inches of body diameter is the most ideal.
  3. Choose that which uses a quartz sleeve. Quartz sleeves are important as they could entirely separate your UV lamp from the water, therefore avoiding shock and damage that may occur when electrical components get wet.
  4. Make sure that the UV sterilizer has a remote power supply. You would want to make sure that the power supply is kept as dry as possible for your safety and to avoid damage to your aquarium and your UV sterilizer.

Best UV Sterilizers for Reef Tanks

Now that you know the benefits of having UV sterilizers and some tips on buying one, here are all the best UV sterilizers you can find to expand your options:

1. AquaUltraviolet 15 Watt Aquarium UV Sterilizer

AquaUltraviolet 15 Watt Aquarium UV Sterilizer

If you own a moderate-size tank, then you might find this UV Sterilizer appropriate for your needs. Tanks of moderate sizes require inline UV sterilizers than the hanging ones. Designed to support flow rates that could be slower than 240 gallons for every hour, this sterilizer would work best when you control the flow rate of your tank and the dwell time to achieve complete sterilization. AquaUltraviolet Advantage 2000+ is also best for tanks that could hold up to 75 gallons of water. 

Lightweight and compact, this unit has a diameter of three inches to ensure that all parts of the tank can be reached by the UV light it emits. To ensure durability, its external tubing is also made out of heavy-duty PVC plastic. Its barb-style output and input also make its installation relatively easier. However, the unit does not have any mounting tubing.


  • Very easy to set up
  • Not very noisy
  • Durable and sturdy
  • Three-inch diameter


  • No mounting tubing or bracket
  • No light to signal if it is already working

2. AA Aquarium Internal UV Sterilizer

AA Aquarium Internal UV Sterilizer

This is one of the best machines to eliminate cloudiness and help remove bacteria and algae in your tank. Useful for aquariums that are 50 gallons or less, this could prevent algae bloom and the presence of yeast. Because the unit is pre-assembled, then the installation is easier. You can do it in less than 10 minutes. This features LED lighting that could signal if the bulb needs replacement. 

Sealed and secured, the bulb would never leak and, when replaced, would also allow for the replacement of the housing, which is usually worn away by UV lights. What helps this unit maximize sterilizing time is that it supports a flow rate of 50 gallons per hour. Since it is listed for product safety, you can be assured that you’re secured when dealing with this unit.

AA Aquarium Green Killing Machine comes with 4 pieces of sponge pre-filter and a three-year warranty.


  • Could clear tank quickly
  • Long-lasting UV bulb
  • UV-bulb is sealed and secured
  • Easy installation
  • Could support your average aquarium


  • Maybe too small for some aquarium

3. TetraPond GreenFree UV Clarifier

TetraPond GreenFree UV Clarifier

This is one of the UV Sterilizers that could support the aquarium of large gallons. With its 9-watt UV-C bulb, this machine could quickly eliminate green water and could work for tanks of up to 1,800 gallons. After installation, the water in the tank would clear up usually within one to two weeks.

Its green housing is made out of durable plastic and could cleverly blend with the aquarium landscape because of its color. Its hose barb could also accommodate Id tubing of sizes 1″, ¾”, and 1 ¼”.

Because of the window on its housing, it would be easier to check the UV light. However, due to the inlet and outlet being on the opposite sides of the body, house routing could get tricky compared to units whose outlets and inlets are situated on the same side.

This unit could work for tanks with a water flow of up to 900 gallons per hour. Its UV bulb is also relatively long-lasting, with an 11-month continuous operation capacity. This also comes with replacement bulbs and other parts like a 15-foot power cord, which is long enough to prevent getting wet.


  • Very effective in controlling algae
  • The power cord is long enough
  • It comes with a three-year warranty
  • Price is affordable


  • There are some units with broken UV bulbs
  • Inlets and outlets are on opposite sides

4. Coralife Turbo-Twist UV Sterilizers

Coralife Turbo-Twist UV Sterilizers

This UV sterilizer could remove all free-floating parasites, algae, and other microorganisms in the aquarium water that could harm the fish. Its unique twist flow design allows increased water exposure to UV light rays, which further increases the unit’s effectiveness since it could reach most parts of the water. This UV sterilizer may be used for aquariums, both saltwater and freshwater, up to 500 gallons in size. 

The unit comes with a Coralife 36W UV bulb. Also, it has mounting brackets that may be used for hang-on or inline applications. To work best, it needs a water tank flow of 300 to 900 gallons per hour. Turbo twist is not included.


  • It comes with mounting brackets
  • Easy to install
  • Would work both in fresh and saltwater


  • Leaking from the internal chamber are observed by some

5. SunSun UV Sterilizer Submersible Filter Pump

SunSun UV Sterilizer Submersible Filter Pump

This is a submersible unit that could cater to tanks up to 75 gallons, allowing effective UV control that could clean bacteria or algae in your aquarium. Because this unit is ready to install, you would not need any circulation pump or additional tubing. This UV sterilizer features pre-filter sponges that could capture debris, therefore optimizing UV exposure. 

To make sure that organisms are directed past the UV lamp, the built-in pump is also installed. You can install this in a vertical or horizontal position and may be used for fresh, saltwater, and garden ponds. It is advised that to optimize the unit’s performance, and bulbs must be changed yearly.


  • Very easy to assemble
  • Features pre-filter sponges
  • Could clean aquarium easily


  • Reports of the burning of the plastic housing

Final Thoughts

Choosing the best UV sterilizer for reef tanks would be easier when you are provided with many options and guides on how to buy one. However, it must be noted that while UV sterilizers help clean free-floating algae, they could not be used as a replacement for filters. UV sterilizers, however, are essential to complement this purpose of aquarium filters. This is to make sure that the water is clear and small organisms that the filters could not clean are removed by UV sterilizers. Hopefully, these options would help you identify the best UV sterilizer that would suit your aquarium, which could surely keep it clean and safe for your fish species.

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