# UV or not to UV that is the question ??



## shaky76 (Apr 30, 2008)

Hi People :thumb:

Just a quick question on how many people use or dont use a UV STERIZILER :-? , what are the cons on using one?

Regards

Shaky76


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## 24Tropheus (Jun 21, 2006)

Cost.
Running cost.
Needs to be high turnover, high spec to make a difference.
Kills all bacteria, not just the disease causing ones.
Fish may not develop normal immunity to disease and become ill when sold on if mixed with other fish.
Useful for controlling disease out brakes in single tanks but may be best to choose to switch em off when things are OK.

Very useful if running a multi tank filter system to help stop disease getting from one colony to another or from new fish to old.


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## PsYcHoTiC_MaDmAn (Dec 26, 2005)

pros,

can kill of free swimming parasites, so can kill ich before it infects other fish. HOWEVER this doesn't stop skin to skin type transfer, 
kills free floating algae (wont make a difference on stuff on rocks and dÃ©cor, but will clear up green water)
good for preventing disease to spread from one tank to another on centrally filtered tank racks.
of particular value for protecting fish/inverts that are highly susceptible to certain medications.

cons.

cost, both setup (their not cheap) and running costs
interfere with some medication, so would need to be turned off when treating for some diseases.
theoretically not needed in a well stocked well maintained tank. more of a luxury

just a few things to clarify on *24Tropheus* post


> Kills all bacteria, not just the disease causing ones.


all bacteria (as far as I'm aware anyway) are sensitive to light (especially UV) so they are mostly found in the dark. therefore the percentage that is free floating through the water is much smaller than the stuff colonising the filter media and substrate etc. "bad bacteria" and viruses need hosts so will have to search for victims, and so are more affected by the UV as they would be more likely to be free floating.



> Fish may not develop normal immunity to disease and become ill when sold on if mixed with other fish.


bacteria and viruses will still be transmitted by fish to fish contact, so they will have some resistance from that. even with the UV, there will still be a small amount of baterial/viral activity within the tank, however as the UV will keep the numbers down it leads to the immune system being attacked less meaning that the diseases are fought off, so they have the immunity

I've hears the argument that if fish are kept in a UV sterilised environment they lose their immunity, but this is complete nonsense as all these people buy from the LFS's (who a large proportion use centrally filtered UV systems), and who have bought fish that have been stored and shipped from wholesalers who will also have used UV.

and I wouldn't be surprised if a large percentage of large scale breeders use some form of UV filtration


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## RyanR (Apr 29, 2008)

Despite not having one (yet), I'll throw in my opinion:

I had a similar question to yours: "Is it worth it?"... until our severums caught a weird bacteria/fungus on the tips of their fins that just won't quit. After three weeks of constant water changes and dosing with salt, Melafix and Pimafix, I'm sold on the utility of the UV sterilizer.

I know that a sterilizer may not have prevented this disease/infection, but it couldn't have hurt. It's true that it also won't prevent all future disease, but if a sterilizer prevents just one more outbreak of anything, it's money well spent.

We threw a *lot* of money at meds and hospital tanks. The next fishy purchases with be inline UV units for both of our tanks.

-Ryan


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## Toby_H (Apr 15, 2005)

Iâ€™ve been using UV lights on some of my tanks for 5+ yearsâ€¦

The ONLY Con I have experienced with them is the costâ€¦

Blue Dempseys are known to be more susceptible to parasitic based problems than most other fishâ€¦ For that reason Iâ€™ve raised most of my Juvi Blue Dempseys with UV lightsâ€¦ but keep them as adults without UVâ€¦ This proves to me that the idea fish raised with UV lights damages immunity is complete nonsenseâ€¦

I do not use UV lights on brand new set upsâ€¦ as I want beneficial bacteria to have chance to spread itself throughout the tank. But once a tank is established, I have never once had an issue with the UV light damaging the beneficial bacterial coloniesâ€¦ Fear of this is based on a lack of understanding about bacteriaâ€¦

I have added a UV light to a tank that is infected with ick on many occasionsâ€¦ Every single time the ick has gone away within a 1~3 daysâ€¦ Not once have I lost a fish due to ick when using UV lights to rid the tank of ickâ€¦

I have added fish with ick to established tanks with UV lightsâ€¦ I have seen the ick spread, but as stated above, it goes away within 1~3 days and Iâ€™ve not lost any fish from ick in this processâ€¦

Although UV lights only kill algae which is free floating, I find that algae does not thrive in my tanks with UV in the same way they do in tanks without UV (when other conditions are similar).

UV lights will affect some medications. I donâ€™t personally use meds in my tanks so I have no personal experience as to which ones are affected.

There is a lot of bad information out there about UV lights. Be cautious who you listen to and verify that they have EXPERIENCE using them and not just a bunch of internet â€œknowledgeâ€


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