My UV bulb and housing after exactly one year


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It is said that a UV bulb will not really be effective after about a year. Maybe even less. I have had a pump with UV bulb built in in my pond for almost exactly one year. About a week ago I noticed my crystal clear water was starting to turn pea green. Today I took the pump apart and here is what I found. It looks to me like the bulb is burnt out and you can see that the glass is heavily coated with calcium or something. I made the mistake of cleaning off the glass before taking the picture too, it was actually worse. This should help show why a UV bulb is no effective after one year.

 

sissy

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did you leave it on during winter .I see most on here just turn it on for a couple of weeks in the spring and that's it .Don't know much about them since I don't have one .So it cleans off and heard that also quartz glass should only be cleaned with vinegar and water .Not sure though ,I happened to see it on that tanked show on tv .
 
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Actually the pump was out of the pond for about 4 months so it wasn't running then. Well, I cleaned the glass with cleaner.... oh well hahaha. Also it is built into the water pump so it runs 24/7 just like the pump.
 
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Good post DP.
How about posting a picture of the quarts sleeve after you cleaned it.
My old UV unit that was built into a pressure filter use to also get a dark residue buildup inside the sleeve, although the calcium buildup was never as bad as yours is showing.
 
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Sorry I put everything back together and back into the pond already. The quartz housing is now clean. Took some chemicals tho! Hope that's not bad. I was sure to rinse it real well before putting it back into the pond.
 
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Many years ago I saw that exact thing after only a couple of days of running a brand new UV. Frosted glass, only where the UV light would have been, not on the edges. Very uniform, very white. If I remember right, I expected it to be calcium and poured some acid on it expecting it to bubble, but it didn't (if I remember right). I think I just cleaned it with just water. It came off easy in flakes, like it wasn't that well attached.

I was seriously bummed, there's no way the UV was going to work because I assumed the glass would frost over again in a few days...why wouldn't it? Same pond water, same UV. I checked it regularly but the frost never appeared again even over the next couple of years.

Would be great if you could confirm this does or doesn't react with acid. Vinegar should be good enough. Been driving me crazy for years.

In all the years since I've only seen one other post from someone. I found a plausible scientific explanation once, but then pretty much completely forgot it. I think maybe it had to due with the high temp of the bulb causing something to precipitate. These bulbs can run extremely hot internally. But that didn't explain why it didn't return. My only guess was there was something about the surface of the glass that allowed precipitation or not. Same reason Mentos make soda foam. When I cleaned the glass the texture was changed and it never happened again, although I wish it had so I could have done some experiments.

Given your picture, the other post and my experience the thickness of the film seems to always be the same. A bit less than the thickness of paper. Very uniform, a bit rough but no bumps.

Any ways, I would check it again in a few days and then maybe once a month. I can appear quickly.
 
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Waterbug said:
Given your picture, the other post and my experience the thickness of the film seems to always be the same. A bit less than the thickness of paper. Very uniform, a bit rough but no bumps.

Any ways, I would check it again in a few days and then maybe once a month. I can appear quickly.
Yeah that pretty much describes the film. I will check it again in a few days just for kicks.
 

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