UV light degradation?

[hmmmmm]

I have an older 30w UV light laying around, it works but i dont know the age of the bulb (Replacement bulb is €100). I only have a small tank (55 gallons) and im considering using it on there. The idea being that even if its an older bulb thats only putting out half of its original capacity, its still going to be effective because of the smaller volume. Cant find much though on degradation numbers. Other than a manufacturer stating that is looses 20% after the first year. But what if you oversize the UV, what about the years after that? 40% at year 2, 80% at year 3? Without these numbers there is now way of knowing when to replace the bulb. Anyway of measuring the output of these bulbs? Or has anyone done any testing on this? Ive seen the BRS testing on T5 bulb life wich was very helpfull, hoping something simular exists for UV.

https://www.aquaristikshop.com/aquaristic/hw-UV-Steriliser-1000-30-watts/208012/

 

[Quietman]

Not aware of any degradation testing as we've seen with T5. But you're logic is correct. That said I rely on my oversized UV heavily and at the 14 month point bought a bulb. $100 or so is great deal to make sure my dinos don't come back.

 

[Timfish]

It's been a few years since I looked but I couldn't find any info either. I'd think it would provide you some protection in the application you've described. I'd use a turnover rate of maybe 2 turnovers an hour. I'd be sure to clean it well too.

 

[Malcontent]

I bought a UV-C meter awhile ago but haven't played with it. But the idea was to be able to determine which bulbs still had useful life. Safety glasses required, of course.

 

[hmmmmm]

Ok, so the only way would be to get a UVC meter, measure from a set distance to a new bulb, and do the same over a number of years. Easy enough Too bad no one has looked into this, now im thinking a lot of people are getting screwed, the use of UV is already heavily debated. But im hearing a lot of people wanting to use it but the 1 year bulb life holding them back. Maybe you just need a bigger UV, lets say 30w instead of 10, and your good for the next 3 to 4 years, that would make it lot more usefull..

 

[Cory]

Put a banana peel near the light if it burns its still good

 

[Sshannon]

Uv bulbs decrease in efficiency over time as they have a limited amount of usable mercury in the bulb. Over time, the mercury oxidizes and binds to the interior surface of the bulbs making the transmission of uv light less and less.