Fish disease and nuisance algae are probably among the biggest and most distressing problems fish keepers face.
Using a fish tank UV sterilizer can go a long way to helping reduce these problems or alleviate them altogether.
UV sterilizers can be used in both freshwater and saltwater aquariums.
Table of Contents
Benefits of a Fish Tank UV Sterilizer
So what are the benefits of a fish tank UV sterilizer? A UV sterilizer cleans your tank by killing off harmful microorganisms such as parasites, viruses, and algae as well as leaving your tank crystal clear. Unlike the tank in the pic below:-
How Does a UV Sterilizer Work?
A UV sterilizer contains a special Ultra-Violet light bulb that emits light at 254 nanometres. This light wavelength damages small life forms such as bacteria, viruses, parasites which can lead to common fish diseases and also algae.
The UV light mutates their DNA making them unable to reproduce meaning the growth and spread of these harmful microorganisms are halted.
As the light is harmful to our eyes and potentially cancerous, the UV bulb is contained within a sealed unit or inside a filter. Tank water passes around it and as it does so, the light irradiates any microorganisms passing by.
As the UV light only affects any free-floating microorganisms in the water that pass through the sterilizer, it has no effect on fish, invertebrates, plants or corals or any good nitrifying bacteria that reside in your filtration, rockwork and substrate.
Types of Fish Tank UV Sterilizers
UV sterilizers either reside within the filter itself or are an external tube with in-and-out pipe connectors where water is pumped through from an external filter or return pump.
Strength of Fish Tank UV Sterilizers
When choosing a UV Sterilizer it’s important to understand that its effectiveness depends on its ability to expose the microorganisms to enough UV light.
The slower the water flow through the UV sterilizer the better so select one that will cope with the flow rate from your pump or filter.
Also, take note of the bulb’s strength as the higher the bulb’s wattage, the more radiation it will expose the microorganisms to.
Good fish tank UV sterilizers will have a recommended aquarium volume and maximum recommended flow rate in their specifications.
Recommended Fish Tank UV Sterilizers
Freshwater
 | Fish R Fun UV Sterilizers Green Killing Machine | Check pricing on eBay >> *Free UK Delivery |
Saltwater
 | Eheim Reeflex UV Marine | Check pricing on eBay >> *Free UK Delivery |
Caution: Do not use a cheap light sold as a UV sterilizer.
These lights may appear attractive because they are cheap but they are not genuine UV light bulbs.
If they were they would be extremely dangerous to both you and your tank inhabitants.
Avoid!
Fish Tank UV Sterilizers FAQs
Will a UV sterilizer harm my fish? – No. As the UV light only affects any free-floating microorganisms in the water that passes through the sterilizer, it has no effect on fish, invertebrates, plants or corals.
Will a UV sterilizer kill good bacteria? – No. Good bacteria reside in your filter media, rocks and substrate and not in the water column. Therefore it will not pass through a UV sterilizer and will not be affected.
How long should a UV sterilizer be on in an aquarium? – You should run a UV sterilizer 24 hours a day. An exception would be when starting a new tank when you wish to encourage good bacteria as it takes time to establish itself in your tank.
Some medications may also stipulate that any UV sterilizer should be turned off.
Will a UV sterilizer clear cloudy water? – Yes. Cloudy water is usually caused by a bacteria or algae bloom. A UV sterilizer will neutralise the microorganisms that cause this and your tank should clear within a few days.
How long do UV sterilizer bulbs last? – Around 6 -12 months. After this time its ability to kill bacteria will slowly diminish and you should replace it.
What size UV sterilizer do I need? – Typically you want as many or more litres per hour passing through the UV as you tank’s total volume. Take note of the manufacturer’s recommended aquarium volume and maximum recommended flow rate.
Is there a downside to UV sterilizer? – Just be aware that a UV sterilizer may make certain medications ineffective. You should always read the instructions that come with any medications and as a precaution turn off your UV sterilizer when treating your tank.