westwind77
Member
I was curious how long MH bulbs last? Are they good until they burn out or do you have to replace them every year? (250w)
Thanks!
Thanks!
How long to MH bulbs last?
- Thread starter westwind77
- Start date
stanlalee
Active Member
I've only seen one test (but it was like 8 bulbs) and it showed MH bulbs lose the majority of what they are going to lose in PAR the first 3 months and after that the drop off is extremely slow and small. basically once you past the 3 month mark there wasn't much difference is PAR between a 8 month old bulb and a 2yr old bulb. If you have a good performing bulb and there's no unpleasing color shift (doesn't turn ugly on you) you can use them for years but if you want peak performance you should probably change them twice a year. as far as burning out, you cant wait for that. the bulb might outlast you.
stanlalee
Active Member
Originally Posted by natclanwy
http:///forum/post/2904889
I haven't seen the study that stanalee is refering to but the studies I have read show that the color spectrum of the bulb shifts and most bulbs at the 11-13 month range are at the end of their useful life as far providing the most useful light for corals.
thats true, I was reffering to PAR. they said 20k bulbs were more likely to shift color sooner than whiter spectrum bulbs.
http:///forum/post/2904889
I haven't seen the study that stanalee is refering to but the studies I have read show that the color spectrum of the bulb shifts and most bulbs at the 11-13 month range are at the end of their useful life as far providing the most useful light for corals.
thats true, I was reffering to PAR. they said 20k bulbs were more likely to shift color sooner than whiter spectrum bulbs.
machinfrontofu
Member
MH bulbs are pesty! but i love the way they look!
i change mine every 6 months or so
i change mine every 6 months or so
wattsupdoc
Active Member
Originally Posted by natclanwy
http:///forum/post/2904889
I haven't seen the study that stanalee is refering to but the studies I have read show that the color spectrum of the bulb shifts and most bulbs at the 11-13 month range are at the end of their useful life as far providing the most useful light for corals.
Originally Posted by Stanlalee
http:///forum/post/2905146
thats true, I was reffering to PAR. they said 20k bulbs were more likely to shift color sooner than whiter spectrum bulbs.
OK I think I remember seeing the same study, but dont recall exactly what the results were. I do however remember taking from it that after 1 year(depending on ballast and hours of use of course) a change of bulb would be in order. HOWEVER, your two posts in my mind contaridct each other.
The "useful" part of what the lamp provided is the radiation(PAR)...Different colored light contains different levels of PAR, the intensity being equal...With the higher levels being (generally speaking) towards the color of daylight, which is 55000K. Moving either dirction brings you closer to either ultraviolet(UV) radiation, or Infared radiation(IR). So a color shift in the bulb would definetly result in a change of radiation. Now, DIMING of the bulb would result in a loss of PAR, however, after the burn in process, I dont believe the bulb will dim very much.
http:///forum/post/2904889
I haven't seen the study that stanalee is refering to but the studies I have read show that the color spectrum of the bulb shifts and most bulbs at the 11-13 month range are at the end of their useful life as far providing the most useful light for corals.
Originally Posted by Stanlalee
http:///forum/post/2905146
thats true, I was reffering to PAR. they said 20k bulbs were more likely to shift color sooner than whiter spectrum bulbs.
OK I think I remember seeing the same study, but dont recall exactly what the results were. I do however remember taking from it that after 1 year(depending on ballast and hours of use of course) a change of bulb would be in order. HOWEVER, your two posts in my mind contaridct each other.
The "useful" part of what the lamp provided is the radiation(PAR)...Different colored light contains different levels of PAR, the intensity being equal...With the higher levels being (generally speaking) towards the color of daylight, which is 55000K. Moving either dirction brings you closer to either ultraviolet(UV) radiation, or Infared radiation(IR). So a color shift in the bulb would definetly result in a change of radiation. Now, DIMING of the bulb would result in a loss of PAR, however, after the burn in process, I dont believe the bulb will dim very much.
natclanwy
Active Member
I think I found the study Stanalee was referring to, here is an excerpt that might answer your question Doc.
Of course, light intensity is only part of the story. I had no way of accurately assessing the changes, if any, in the bulbs’ spectral shift. The light spectrum, however, has been found to be far less important to corals' growth than total PAR levels.20 Changes in spectrum definitely affect the aquarium inhabitants' apparent color, though, and conceivably have a longer term effect on the corals' pigmentation. These effects are somewhat subjective, though. It may be that you would want to change the bulbs before their light output requires it simply because you don’t like how they appear. So far, though, in my tank I have not seen a noticeable change in the bulbs’ color, nor has the corals’ apparent coloration deteriorated.
This study isn't a very complete since it only covered DE bulbs and only one manufacturer, but regardless according to this study the PAR drops significantly over the first few months and then levels off and after one year the bulb still retains 75% of its initial PAR and at the end of two years still retains 63% of its initial PAR value so there is only a 10% reduction over the second year compared to the end of the first year.
Here is a link to the article if anyone cares to read it: Light Output of the Phoenix 14,000K DE MH Bulb Over Time
Of course, light intensity is only part of the story. I had no way of accurately assessing the changes, if any, in the bulbs’ spectral shift. The light spectrum, however, has been found to be far less important to corals' growth than total PAR levels.20 Changes in spectrum definitely affect the aquarium inhabitants' apparent color, though, and conceivably have a longer term effect on the corals' pigmentation. These effects are somewhat subjective, though. It may be that you would want to change the bulbs before their light output requires it simply because you don’t like how they appear. So far, though, in my tank I have not seen a noticeable change in the bulbs’ color, nor has the corals’ apparent coloration deteriorated.
This study isn't a very complete since it only covered DE bulbs and only one manufacturer, but regardless according to this study the PAR drops significantly over the first few months and then levels off and after one year the bulb still retains 75% of its initial PAR and at the end of two years still retains 63% of its initial PAR value so there is only a 10% reduction over the second year compared to the end of the first year.
Here is a link to the article if anyone cares to read it: Light Output of the Phoenix 14,000K DE MH Bulb Over Time