Using Ultraviolet Sterilizer

[vagabond]

Hi reefers,

I would like to know your opinion on using UV in marine tank, be it reef, mix or fish only.

Please kindly share your 2 cents 3 cents worth.

Thank you.

[Tanzy]

Pro - Your fish get a healthy tan.

Con - Waste of money.

[marcvelous]

Hi Tanzy,

Would just like to find out more on your statement.

Take for example, the Corlaife TurboTwist UV Sterilizer. How is it able to give your fish a tan (since it is sited outside your tank)? Given that you were joking (?) about the tan, why is it that UV is not effective in tackling the ich problem?

I am thinking of getting the TurboTwist and seriously, your comments would help greatly.

Cheers!

[Marineman]

UV kills bacteria which causes ich AND also live food/plankton for your corals

[lastmanstanding]

IMO, it will kills all living organism floating in the water.

i believe that UV only kills suspended Ich bacteria in the water and not those that is already on the fish....

am i right?

hehe...

[Tanzy]

Aquarium UV filters are a joke. They do not allow sufficient contact time nor do they have sufficient power to kill much. The layer of the water around the UV tube is also too thick for the UV to penetrate. Commercial UV filters are huge, many times more powerful and are very very long.

Healthy fish don't get ich anyway. Ich is not a bacteria so it will take a longer exposure or more power to kill it.

[nim75sg]

Following are my thoughts about UV Sterilization and arguments have been put forward many times both in marine and freshwater keeping that UV radiation can cause problems within a closed system.

Beneficial bacteria are killed along with potential live food for filter feeders. The fact remains, however, that beneficial bacterial require a surface to colonize and this allows for their metabolic rates to work to the optinium ie replication.

The killing of filter feeding food is of no consequence as we will actively adding food all of the time anyway.

The theory behind UV is that if bacteria or algae are exposed to UV light between certain spectrum (I think is about 220 to 250nm), then the DNA of the organism is damaged and unable to replicate itself and so dies during cell replication.

Therefore if we pass our aquarium water (marine or tropical) over this light source we will clean that water body of potential pathogens and algae blooms.

As long as the water velocity (from your pump) through the UC Sterilizer is lower that a critical level than any organism is exposed long enought to cause permanent damage.

This method is very effective but is not 100% effective as the theory depends on the whole water body passing through the UV but as we all know that all aquariums have dead spots where there is low water movement and does not pass through the UV.

Here potiential bacteria or pathogens or whatever could reside long enough for infection.

However, the risk of disease is greatly reduced.

My 2 cts .. Reduce the risk of disease and install a UV Sterlizer.

[Tanzy]

I will quote myself here from http://www.sgreefclub.com/forum/index.php?showtopic=7393

The water treatment provided by the aquarium UV tube is insufficient to kill parasites or bacteria to a significant extent. There isn't enough strength of UV radiation and the passage time is too short. Not to mention that the water layer around the UV source is too thick.

To kill 50% of E. coli, you need at least 350 milliW.s/cm2 using a commercial strerilizer, whereas I estimate that a 30W aquarium sterilizer at best offers 120 milliW.s/cm2. It will take more energy or longer exposure to kill parasites which are larger than bacteria and take into account the suspended particulates and ions there are in seawater.

If you have seen those sterilizers at Coralfarm then you know how big they have to be to be effective. It's not that big because they have a larger volume of water to treat but because you need sufficient exposure to kill the parasites. To deal with more volume, they use more UV units. Compare the units you get from LFS with the ones you see at Coralfarm and you can estimate how effective or ineffective the aquarium units are.

Apparently, some reefers are too foolish to search.

In case some are wondering, milliW.s/cm2 is milli watt seconds per square centimeter.

I will admit I made a mistake here and correct it now that I have reviewed it, microW.s/cm2 should be corrected to mW.s/cm2 or milliWatts.s/cm2. I've mixed up the units. Corrections have been highlighted by italics.

Edited August 6, 2004 by Tanzy

[FuEl]

Yep...Ich is a protozoa. Much bigger than bacteria.

[lastmanstanding]

Yep...Ich is a protozoa. Much bigger than bacteria.

oh...

thanks for correcting me....