UV Sterilizers?

[greg4163]

I read somewhere on this forum that OrionGirl said that using a UV sterilizer was not recommended because it kills off all kinds of beneficial organisms? This has me puzzled because wouldn't the use of a protein skimmer have the same affect of removing these organisms? And besides I'm under the impression that a UV sterilizer will only kill organisms up to a certain size. I am planning on setting up a Fish only w/live rock using a protein skimmer & UV, I've always had good luck using UV in my fresh water setup.

[OrionGirl]

Depending on the UV settings, it will kill pretty much everything that goes through it, meaning all the free floating critters in the water column. A lot of this stuff is a food source for your filter feeders, so that's not a good thing for them. Also, many beneficial critters spawn via clouds of sperm/eggs--going through the UV kills them, which isn't necessarily bad, but it means you don't get self sustaining or spreading populations.

UV set low enough not to kill larger organisms is not going to efficiently kill the smaller ones, which means the UV isn't even doing the job you wanted.

I know several people who had serious nitrate problems after installing a UV to run full time. Turning off the UV brought down the nitrates.

I do think that a UV is useful in a quarantine tank, just not for a show tank (for SW and FW). Ask yourself why you're running the UV--because UV doesn't do anything to improve quality of water. All it doesn is kill things--some good, some bad. Since parasites are best dealt with in quarantine, and most other "UV-treatable" problems can be better and more easily treated with other methods, they just aren't needed IMO.

For skimmers--yep, they do remove some of the good dissolutes along with the excess protien. However, a skimmer really does remove them, and the iodine, etc can be easily replaced with regular water changes.

[mogurnda]

I generally agree with OrionGirl. There are others who swear by UV units, which I interpret to mean that they don't do too much harm.
A couple of things about skimmers. First, you have to have an incredibly good one to strip all plankton and bacteria from the water. Skimmers are designed to pull out charged molecules, not particles, and most let plankton go right through. Nonetheless, I have my skimmer on a timer that goes off at dinner time. This allows the filter feeders to get the debris and liquid from the food. It stays off until a few hours after lights out, so that larvae released by the shrimp, porcelain crabs, etc have a chance to get eaten.

[Kit Walker]

I swear by my UV sterilizer. My reef tank had a whitespot outbreak which I couldn't control. In the end I didn't think removing all the fish from my reef tank for 4 weeks was a reasonable solution(try catching them as they hide amongst the LR and coral!), so I bought the UV. The whitespot disappeared and has since never re-occurred. I do agree that it does also kill beneficial organisms. I also feed my fish live brine shrimp regularly from the LFS, so there is always a chance of pest introduction. To me the UV sterilizer is my insurance.

On the other hand if your tank runs fine without one and your quarantine method works then I wouldn't outlay the money for UV. If you are careful like Oriongirl then you likely shouldn't need one. I guess they are like skimmers in the way some people swear their tanks run fine without one, and others swear they wouldn't be without one! If you're on a good thing stick to it!