Do UVs Really Prevent Disease Spread?

[MattyM]

I was recently part of a chat where someone was thinking of filtering 2 tanks with one filter. So I asked - wouldn't that spread a disease in one tank to both? He replied, the inline uv light will take care of that. 

Is that true? Can a UV prevent the spread of any sort of disease? I know they can be good for the general health of a tank, but this seems to rely on them too much.

[Guppysnail]

I’m not a scientist but my understanding is if they are strong enough to kill algae they are strong enough to kill bacteria. Time in contact counts so higher flow is less efficient. Bulbs getting old or caked with deposits are also less efficient. 
parasites and things like worms and anchor worms I am not sure. They do not sterilize ALL the tanks water at once. Bacteria reproduces rapidly. 
would I rely solely on UV to prevent the spread of things from tank to tank with unknown fish or quarantine fish…NO. However I do use them occasionally when I have a concern or in a qt. 

Edited November 17, 2022 by Guppysnail

[The endler guy]

On 11/17/2022 at 2:07 PM, MattyM said:

I was recently part of a chat where someone was thinking of filtering 2 tanks with one filter. So I asked - wouldn't that spread a disease in one tank to both? He replied, the inline uv light will take care of that. 

Is that true? Can a UV prevent the spread of any sort of disease? I know they can be good for the general health of a tank, but this seems to rely on them too much.

uv works by killing off microbes, personally I think it has its ups and downs (theoretically, I haven't done nearly any research and never used it, so this is just my speculation)

[Odd Duck]

I would expect an effective UV filter to limit disease but not eliminate it.  Bulbs can go out, get caked with debris, etc, so I would never rely on one to be 100%.  Is it a great tool to help control disease?  Yes.  Is it 100%?  No way.  Not even with meticulous maintenance.

[TheSwissAquarist]

UV is often used to clean rainwater off a roof in a closed water-supply system to eliminate all the potential pathogens and bacteria from the bird 🦅 poop up there. Fun fact I researched for my science competition project (nerd & proud!). ‘The effects of climate change on water and how to adapt to them’

[meadeam]

Not to mention broad spectrum UV, which is what would be required to reliably kill the most pathogens and deactivate viruses, is not safe for people.  I don't know if aquarium UV products emit broad spectrum though.  

[TheSwissAquarist]

On 11/18/2022 at 5:59 PM, meadeam said:

Not to mention broad spectrum UV, which is what would be required to reliably kill the most pathogens and deactivate viruses, is not safe for people.  I don't know if aquarium UV products emit broad spectrum though.  

If it’s not safe for people I doubt it’s safe for fish 🐟 😉 

[Tazalanche]

On 11/18/2022 at 11:00 AM, TheSwissAquarist said:

If it’s not safe for people I doubt it’s safe for fish 🐟 😉 

But you're not supposed to shine any type of UV light directly on the fish, so that part shouldn't make a difference. Aside from the DIY versions, which are designed for a sump, most aquarium style UV systems have the light inside some form of case, with a case design that has the water flow through it.

[Cory]

This is one of those, on paper yes, it would work. In practice, people never match up the slow flow to the watts needed.

Most people do it to try and save on filtration or something.. But running UV at the right levels to prevent disease is crazy expensive. IF this worked, every store, wholesaler and farm would do it and disease wouldn't exist in this hobby. Now can it be used to kill off a decent amount of things? Sure. But many things would live right through passing by an aquarium uv sterilizer in currently environments the way they are designed for the hobby.

[MattyM]

Cheers @Cory - I was wondering that too, if it really worked it would be much more common. Thanks everyone for chiming in!

[Mmiller2001]

I run one, definitely helps keep water clearer. If it zaps a few bugs, bonus.

[TheSwissAquarist]

On 11/18/2022 at 7:14 PM, Cory said:

But many things would live right through passing by an aquarium uv sterilizer in currently environments the way they are designed for the hobby.

There’s also the argument of pathogens “hiding “ behind particles as they go though the UV beam…

[modified lung]

I've seen studies on ich that say UV works well for keeping it from spreading between tanks but not so well preventing it from spreading within a tank. This is in lab conditions though where they were careful to properly maintain UV lamps, sterilize equipment used between tanks, and whatnot.

[Sun.singh1991]

UV light at higher wattages will kill basically everything in the water. However, to run it at that strength would be pretty expensive. Also, I would say that using UV can actually weaken the immune systems of fish over time. Since they would not be exposed to as many pathogens. 

[Colu]

Uv works to break the DNA chain's of bacteria and virus to stop them from reproducing I use  a UV steriliser on my gold fish tank that had a persistent green water it completely eradicated the free floating algae I wouldn't trust it to completely kill all harmful pathogens in my aquarium 

Edited November 20, 2022 by Colu