[Subskipper]

When I go to my LFS and talk about my needs and goals I always consider adding a UV filter to my reef tank. Half the people say it's a great idea, the other half say it will cause more problems than it is worth.

Anyone have any suggestions as to whether or not this bit of equipment should be used in a reef tank?

Thanks

Bernard

[Ninong]

UV filters and ozone are in the same category as far as I am concerned. Neither is actually required for the average size reef tank but both are useful and probably a good choice for very, very large home systems and public aquaria.


UV will kill everything that passes through the tube, assuming that it is properly sized and the flow rate is properly set. That means it kills the good, the bad and the merely ugly. This is not a terrible thing but it is not necessarily a desirable thing either. It is a much more understandable thing if you are running an extremely large, extremely expensive system and you want to reduce the risks of parasitic or pathogenic problems.

Ozone, which you didn't ask about, is in the same category and even more so. There is a certain element of risk associated with ozone and it is better left to those with the proper equipment and controls.

The short answer is that you do not need a UV filter. If you are setting up a fish-only system it would be something worthwhile to consider if funds permit. If you are setting up a reef tank you are probably better off without one. If you are setting up a very large, expensive reef tank, you might want to use one to reduce risks even though it will have unavoidable side effects that you really could do without. The only negative side effects have to do with the fact that it kills off larvae that pass through the tube that would otherwise feed the corals in the tank. A potential negative side effect claimed by some well known hobby authors is that a sterile system is not a natural system and could adversely affect the immune systems of the corals and other inhabitants of your tank. I have not seen any evidence for or against this proposition but it is an interesting consideration.

[Subskipper]

Ninong,

Thank you for the quick response. The only real reason I was considering the UV was the outbreak of cloudy eye and marine ich that has hit my tank and already killed three inhabitants.

I do weekly water changes (5-10G), I use pure water through a filter system designed for aquariums, I clean my filter every few months, I have 120lbs of liverock for natural filtration yet the disease has struck and killed a Blue Hippo Tang,Purple Gramma, and a flame angel.

I am concerned because have never lost a fish, even through cycling. I fear that this problem will wipe out my tank.

Suggestions? Thanks in advance!

Bernard

[Ninong]

If you install a large enough UV filter with the right flow rate you could kill off any Cryptocaryon irritans parasites during the free-swimming stage that happened to pass through the UV tube. Any that manage to attach to a fish before passing through the UV tube would be unaffected. There is a big difference in the UV dosage that will kill off floating algae spores and the dosage necessary to kill off protozoa. You can probably find the correct dosage by checking the websites of the more reputable manufacturers, such as Aqua-Ultraviolet.

Installing an inadequate UV lamp or running the water through too fast will not kill off the parasites. You need to know the minimum wattage and dwell time to determine the minimum amount of UV radiation necessary to do the job. An 8-watt UV lamp may be a complete waste of money. Even a smaller aquarium probably needs at least a 25-watt UV lamp to kill protozoa and other parasites assuming the flow rate is properly set to accomplish the necessary dwell time.

[Subskipper]

Ninong,

If a UV filter is not the right equipment to use than I won't use it I am more interested in doing whatever it takes to solve the problem I am having and avoid it from occuring again. Nothing is more frustrating than having your fish die in what seems to be a stable tank!

Once again, I do appreciate your expertise!

Bernard

[Ninong]

Originally Posted by Subskipper

Ninong,

If a UV filter is not the right equipment to use than I won't use it I am more interested in doing whatever it takes to solve the problem I am having and avoid it from occuring again. Nothing is more frustrating than having your fish die in what seems to be a stable tank!

Once again, I do appreciate your expertise!

Bernard

It's not really a matter of right or wrong when it comes to a UV filter. If you had a properly functioning, properly sized UV filter on your tank before you introduced any fish, chances are you wouldn't have the problems you have now; but there are other ways to reach the same goal.

If you have ich now, the only safe choice is to remove all of the fish from the main tank and place them in a hospital tank for treatment. Then you should allow the main tank to remain fishless for six weeks to allow the parasite's life cycle to be broken. That is the most reliable approach. Some people have reported success with simply feeding food soaked in garlic extract or adding finely minced garlic to the food. That may or may not work but it could be tried if you are so inclined.

There are various ways to treat fish for ich. A search on this board will yield lots of information.

Good luck,