UV Sterilization

!poogs!

Member
So couple years ago I bought a UV sterilizer to combat a green water algae problem in a planted tank. I hooked it up and then thought better of my decision as just being a bandaid solution. Long story short I figured out what changes I needed to make and the green water went away, so did the UV sterilizer.

Fast forward a couple years to recently, had some sick fish related to bacterial infection. Lost a few amazing fish, treated tank with antibiotics for several weeks, made some significant changes to improve the cleanliness of the tank. Tank is blinging better than ever, I thought I had good water before, now it’s so clear I can’t even tell water is in the tank.

So I have this UV sterilizer and today I set it back up in the tank on a timer to run 12 hours a day. I set it up under the premiss that UV light can kill water born bacteria, virus, and fugal spores, why not use it instead of having it around collecting dust.

I searched the forum and couldn’t find the answer I was looking for.

Any one use UV sterilization as part of their ongoing water conditioning regiment? What has been your experience in your tanks using it in comparison to how your tanks were before, have you noticed a difference?

If you don’t use it, why not?

I know on the saltwater side, it seems it is used more often than not.
 

Redshark1

Member
I can only comment on freshwater systems.

Bacteria that infect fish are Commensal Bacteria and therefore UV filters have little affect on them.

UV filters are useful to clear green water in a new tank or after pertubation.

UV filters can effectively clear the water allowing the macro-plants to grow vigorously and therefore utilise the nutrients that caused the quicker growing green water to form in the first place.

They can then be switched off when the system is stable and not subject to further disruption.

Unstressed fish kept in optimal environmental conditions without unsuitable tankmates are not generally at risk of disease except possibly in old age.

Reasons I have for not using my UV filter:
1. Cost
2. Maintenance
3. Tankspace
4. Wasteful
 
  • Thread Starter

!poogs!

Member
Okay, that’s pretty definitive.

So are you saying ALL bacteria that infect fish are commensal bacteria?


Since we know the majority of fish disease are aerobic infections, does the commensal relationship of the bacteria exist between the bacteria and the oxygen in water molecules or does it always exist between the bacteria and the host? Humans, fish, all living things are full of commensual bacteria. So are you saying ALL bacteria which make fish sick are already living on fish as a host, and is it the colonization of these bacteria which make fish sick? That is to say aquarium fish are unique living things and are not infected by environmental sources of bacteria, only ones they are the host of.

Is it possible some of the bacteria responsible for killing fish are pathogenic bacteria?

I think a fair statement is that some of the bacteria which are responsible for infecting and killing fish come from 3 possible sources. The environment (the water), the dermis of the fish, and internally (the later two possibly sometimes having a commensal relationship with the host fish). I do agree that parasites, poor water quality, and stress cause a state in fish whereby they become more susceptible to bacterial infection from one of the three sources mentioned above. So if UV sterilization kills water-born parasites and bacteria, this would lend itself to better water quality which the inverse is a cause of stress in fish, wouldn’t it?

So back to my original question...

Any one use UV sterilization as part of their ongoing water conditioning regiment? What has been your experience in your tanks using it in comparison to how your tanks were before, have you noticed a difference?
 

aeneas

Member
!poogs! said:
Okay, that’s pretty definitive.
So are you saying ALL bacteria that infect fish are commensal bacteria?
Since we know the majority of fish disease are aerobic infections, does the commensal relationship of the bacteria exist between the bacteria and the oxygen in water molecules or does it always exist between the bacteria and the host? Humans, fish, all living things are full of commensual bacteria. So are you saying ALL bacteria which make fish sick are already living on fish as a host, and is it the colonization of these bacteria which make fish sick? That is to say aquarium fish are unique living things and are not infected by environmental sources of bacteria, only ones they are the host of.
Is it possible some of the bacteria responsible for killing fish are pathogenic bacteria?
I think a fair statement is that some of the bacteria which are responsible for infecting and killing fish come from 3 possible sources. The environment (the water), the dermis of the fish, and internally (the later two possibly sometimes having a commensal relationship with the host fish). I do agree that parasites, poor water quality, and stress cause a state in fish whereby they become more susceptible to bacterial infection from one of the three sources mentioned above. So if UV sterilization kills water-born parasites and bacteria, this would lend itself to better water quality which the inverse is a cause of stress in fish, wouldn’t it?
So back to my original question...
Any one use UV sterilization as part of their ongoing water conditioning regiment? What has been your experience in your tanks using it in comparison to how your tanks were before, have you noticed a difference?
I'm very much interested in this as well and what were the final conclusions? After lots of reading of various comments and reviews it seems to be unclear whether UV really helps or not... on the other side I read some concerning comments that UV might degrade/chelate various micronutrients that I will be adding to the tank for plant fertilization etc. I would certainly not want to destroy a fertilization effort...
Any thoughts on this?
Do people switch on/off UV sterilizer depending on the days of IE fertilization etc. or what is the general consensus and recommendation here?
 

GlennO

Member
You can find plenty of research on the effectiveness of UV sterilisation. It is used routinely in water treatment facilities, aquaculture, public aquariums etc.
 

RayClem

Member
I have several tanks. I use UV lights in two of them. In one case, I purchased a 24 watt Green Killing Machine because I had a severe microalgae problem last summer in my 55 gallon tank that is in a room with a lot of direct sunlight. I tried removing the algae with a 1 micron filter, but it grew back as fast as I could remove it. I hooked up the GKM and the algae was gone in 48 hours and the tank was crystal clear in another 24 hours. I now run the UV on a timer for 4 hours per day to keep the tank clear.

I purchased a SunSun canister filter for my 40 gallon breeder tank. The filter came with a 9 watt UV light. I run that light for 4 hours per day as well to keep the water clear. The water might stay clear even without the UV, but I have not turned the light off to find out.

So I am using 132 watt hours of electricity per day to power the UV lights. That works out to 4 kwh or about 50 kwh per year.

Typically, UV bulbs last about 6 months. However, using it only 4 hours per day, the bulb should last six times as long or about 3 years. The 24 watt replacement bulb in housing is about $40.

Thus, the purchase and operating cost of a UV light are pretty small in comparison to some of the other things in the hobby. Thus, if you have a UV light already, I would suggest you use it.

BTW- If I were to get an outbreak of ich, I would run the UV light 24/7 for about 3 weeks to help kill any free-swimming tomites in the water column. It won't be effective against any parasites, bacteria or fungus attached to a fish, plant or other surface in the aquarium, but it will help prevent transmission to other fish.
 

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