Using UV Sterilizer in a planted tank

Most of us heard about UV from our textbooks, we know how bad it is for our skin. But have we ever thought about how to use it to our benefit? Thankfully, some people did. Throughout recent decades UV has been used in many practices. One of those lucky practices happened to be in the aquarium.

Using a UV Sterilizer in a planted tank is a convenient way to keep your aquarium clean. Compared to its chemical counterparts, it delivers powerful, precise, and thorough disinfection, keeping your aquarium healthy. 

The use of its cutting-edge technology would enamor anyone, so for the curious minds, we will show you not just what UV sterilizer does to your tank, but also how to achieve it.

What is UV Sterilizer?

To know about UV sterilizers first we need to understand what a UV light is. UV or Ultraviolet light is radiation of small wavelength. The source of UV light is The Sun. Following the US Navy’s guide, Ultraviolet light can be divided into 3 sub-bands: UV-A (350-400 nm), UV-B (280-350 nm), and UV-C (180-280 nm).

What we need on our planted tanks is UV-C and its critical ability to mutate the cell structure. A UV sterilizer uses a bulb emitting UV-C light of 253.7 nm.

Simply, a UV sterilizer is a germicidal lamp emitting Ultraviolet light to repress the growth of particular organisms, shortening their lifespan and might even eliminate them. 

Definitely, those who aren’t hardcore aquarium lovers will treat this as alien technology. But what are we here for?

Do you need a UV Sterilizer for your aquarium?

A UV sterilizer is a great prophylactic for your planted tank, you could even call it an insurance policy. It controls the growth of algae, fungi, pathogens, bacteria, parasites efficiently. You don’t need chlorine or any kind of biocides if you have one of these ruthless machines.

And here is the best part, it doesn’t harm any plants or fish. Good UV sterilizers can even distinguish between beneficial and harmful bacteria, letting the useful ones live.

On many occasions, having a good filtration system isn’t enough. Since an aquarium is always full of nutrients and light, they could be responsible for algae growth if you don’t pay attention. And the sad part is, you will have no idea until it’s too late.

By then it’ll be the cause turbidity, spread spores to create an algae bloom, make a home for parasites, etc. and many other inconveniences. Having a UV sterilizer helps mitigate that.

It’s a good investment of money, if you’re an aquarium hobbyist you won’t be let down.

How does a UV Sterilizer work in your planted tank?

When water is passed through the UV sterilizer, it scans the planted tank for contaminants and exposes them to a lethal dose of UV light, which will alter their DNA by gluing the molecules together, tampering with their cell structure and making them obsolete and unable to reproduce (hence, the term sterilizer).

One thing you should know, UV sterilizer will only affect free-floating organisms, so it’s not going to hurt your plants.

Factors involving UV Sterilizer

UV sterilizers are excellent to keep your planted tank clean, however, that happens if there are some considerations taken into account and it operates in the right manner. These factors will affect the efficiency of the sterilizer which is why you need to be careful about the following things:

  1. The lifespan of the bulb 

The bulb loses 60% efficiency after a year. Replacing them once a year is a must.

  1. Power

The more wattage, the more UV light output you will have.

  1. Length of the bulb

A longer bulb means more spread contact with the water. The cleanliness of the bulb is also another important matter. If any material or film is covering it, then the light will be blocked partially.

  1. Dwell time

If the UV light is exposed to the water for a longer duration, then it will have more effectiveness.

  1. Flow rate

A slower flow rate creates the opportunity for a longer dwell time. But, you need different flow rates to deal with different organisms.

  1. Turnover time

Turnover time refers to the time needed for the total volume of water to pass through the sterilizer, which is very tricky to calculate.

 Thankfully, there is a formula to approximately compute it that is written below:

  1. Temperature

Experts believe 104-110 degrees Fahrenheit is the best. You can use quartz sleeves to insulate the bulb, maintaining a high UV output.

  1. Penetration

UV light will penetrate more through clean waters compared to turbid or saline waters. A good workaround is placing mechanical and biological filters right before installing a UV sterilizer.  

  1. Organism types

While smaller organisms like fungi, bacteria, and other pathogens require a small amount of radiation to be obsolete, something like protozoa would need a much larger amount. The following table explains it neatly:


Killing Dose












Keep in mind that this table only mentions a generalized value, there are also organisms with a high level of UV resistance.

  1. Tank size

A large-sized planted tank needs an equally large UV system, otherwise, you will it won’t cover all the space or create heating issues.

Manufacturers provide information on their products addressing this subject.

The above-mentioned factors affect the UV sterilizer greatly. Try to know everything about these considerations to relieve yourself from nuisances in the future.

Must-have Features

You will see a lot of models in the market. But you’re there for one of the most efficient ones. We believe a good sterilizer should have below mentioned features:

  1. Remote ballast unit
  2. Indicator
  3. Auto turn on in case of temporary loss of power
  4. Emergency shutdown
  5. Quartz sleeve
  6. Add-on couplings which fit easily
  7. Respectable warranty

Maintenance of a UV Sterilizer

Quartz sleeves need regular maintenance, check it every month, and rub some alcohol to clean it. There are wiper mechanisms in some units making the maintenance easier.

Replace the UV bulb every 6 months. Technically they have a lifespan of 9000 hours which is roughly 375 days. But they lose efficiency really quick. The disinfection quality will lower significantly as the months go by. So, 6 months is a good timeframe.

Replace the O-rings every year since they degrade fast. You need to keep your bulbs waterproof.

Get yourself a UV sterilizer!

We’re hoping that our article explains the benefits of using UV Sterilizer in a planted tank; inspires and motivates you to get one. It is one of the best investments you could get for your tank. For a little extra cash, you get to add an extra layer of convenience.

It is a must-buy for an aquarium hobbyist, as it will exponentially elevate the charm of their planted tank. You won’t regret it.

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