# Will a UV CFL work to kill green cloudy water



## DarkCobra (Jun 22, 2004)

Hi Bjielsl, welcome to the forum!

A common blacklight won't do anything to the algae. Neither will an UV LED. They both operate at too long a wavelength of light.

A UV sterilizer bulb operates at a very specific and shorter wavelength, optimized to destroy organic material. Like the part of sunlight that produces sunburns, but even more destructive.

Now what if you get a true sterilizer bulb that fits into a common fixture? As it happens, I have one.

So I attempted to use it to cure a greenwater bloom. Knowing how dangerous the light was, I improvised a shield that water from the HOB filters would flow over, but protect the rest of the aquarium underneath from exposure. Being careful never to look at it without eye protection (it will easily burn your corneas), I ran it overnight.

It did a spectacular job of eliminating the greenwater. But apparently a bit of the light leaked past the shield, and it was enough to burn the tops of all my fishes. Then secondary infections set in. After much medication, I managed to nurse them back to health; but to this day I have several black guppies with noticeable white patches on top.

As much as I like trying to DIY strange things, I admit now it's best not to attempt any DIY UV setup. I'm not aware of anyone else who's done it successfully either. Go with a commercial unit. Or try other methods (blackouts, diatom filtration, etc.), though your chance of success is less.


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## Mr. Appleton (Jul 1, 2011)

Green killing machine worked wonders for me in my turtle tank. It went from not being able to see the turtles swimming inside of it to almost crystal clear within a week. 

However, I found that within about 2-3 weeks of removing the UV sterilizer, the water was getting cloudy again. This time I tried glutaraldehyde dosing and that seems to have cleared up the water on top of helping the plants I have in there grow like crazy  

Best of luck!


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## Jeffww (Aug 6, 2010)

UV is dangerous. Don't mess around with it yourself. You'll get cornea damage if you look at the bulb unshielded even briefly forget the fish your eyes you can't buy at a store.


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## DiscusIt'sWhats4DinneR (Apr 25, 2008)

Bjielsl said:


> I have been reading and from what I can find a UV sterilizer is pretty much the only way to kill "This is a unicellular algae. Water goes cloudy. Sometimes just a green tint, other times it can look like pea soup......A UV steriliser/clarifier or diatom filter will clear it up very quickly and is often the only way to clear it."
> 
> http://www.theplantedtank.co.uk/algae.htm
> 
> I was wondering if I added a UV bulb to the top of the tank if that would kill it?




I have used a UV tube on top of the tank as you say and within 12 hours it killed two 4" angelfish and a number of other small fish. not to mention i woke up with a little sunburn since i sleep about 10 feet from the tank. Do yourself a favor and don't even experiment with it, not worth it. I was using the same type of UV bulb as used in the sterilizers or used for germ killing. i believe it is UV"C", but feel free to correct me. very dangerous and kills anything if it comes in contact with it long enough.


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## HypnoticAquatic (Feb 17, 2010)

uv light will blind everything, yes even a black light can blind us! read on the warning that is why the uv light is in a sealed chamber so no light gets out to do harm to you or your fauna just get the Green killing machine for like 50 bucks at petsmart? or ebay where ever you want and your problem will be fixed.


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## mistergreen (Dec 9, 2006)

I told a new member here a while back not to do it and the guy did it anyway. Not only did he plug in the UV bulb, he plugged in the wrong bulb wattage wise into a wrong ballast. 
What happened next was an extreme high output and an explosion... Half of his face was burnt.

Please stick around and add to the gene pool by not doing this.


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## happi (Dec 18, 2009)

Bjielsl said:


> I have been reading and from what I can find a UV sterilizer is pretty much the only way to kill "This is a unicellular algae. Water goes cloudy. Sometimes just a green tint, other times it can look like pea soup......A UV steriliser/clarifier or diatom filter will clear it up very quickly and is often the only way to clear it."
> 
> http://www.theplantedtank.co.uk/algae.htm
> 
> I was wondering if I added a UV bulb to the top of the tank if that would kill it?


you want to get rid of green water:

change the water more often
increase the water flow and filtration
reduce the ammonia by reducing the fish load and fish food

i used a UV only for a 1 month and it did work very well but i came to found the root problem and it was fixed by doing the above.


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## Abrium (Jan 7, 2011)

yikes, I don't even like reading about the dangers of this stuff. Truely irreversible damage always scares me.


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## Jeffww (Aug 6, 2010)

happi said:


> you want to get rid of green water:
> 
> change the water more often
> increase the water flow and filtration
> ...


Or fresh cut willow branches. They put out roots quickly and sap up nutrients faster than any aquatic plant could ever accomplish. Or do a half strength erythromycin dose....whatever you're up for.


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