# Burnt out bulb, or fixture?



## Fujo (Apr 15, 2012)

Hi,

I'm using a AquaticLife dual T5HO 30" (one 10k, one 420/460nm bulb) on my 29 gallon reef-tank and something has happened with the light. I've had it for just over a year now and just a week ago the light coming out from it appears to be mostly blue. The white bulb still lights up, but normally it's completely overpowering the blue. 

I know this is around the time that I should be getting new bulbs anyways (I've never replaced them) but I've never heard of a dimming white light being a signal that it's time. The other possibility that I was worried about is that something with the fixture itself might be broken.

I'm hoping it just means I need to buy a new bulb, but any other opinions would be great.


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## sooley19 (Jan 7, 2009)

replace the bulb.. if it was the fixture itself it wouldn't work.. and if it was the ballast well none of the bulbs would work so that basically sums up your question right there.. its time to replace them anyways so there shouldn't be an issue


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## wtac (Mar 17, 2006)

+1

The dual T5HO lamps are on a single ballast. If it was a ballast issue, the other light wouldn't be working either.

The "dimmness" of the white bulb is an indication that it's near failure point.

Changing the bulbs on a 9-12month basis keeps a relatively consistent spectral and intensity range before the aging bulb creates problems. Spectral shift (red shift) can cause problematic algae issues and "photo shock" as old bulbs can have an PAR output of half of new bulbs. This issue is increasingly problematic with 6-10 lamp T5HO fixtures than duals.

HTH


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## Fujo (Apr 15, 2012)

That's awesome to hear, probably the best case scenario. I'll definitely be grabbing a new bulb this week. Thanks!!


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## matti2uude (Jan 10, 2009)

Fujo said:


> That's awesome to hear, probably the best case scenario. I'll definitely be grabbing a new bulb this week. Thanks!!


You should change both if they are the same age.


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## badmedicine (Oct 27, 2012)

Don't wait to change your bulbs. If you do the ballast will go. The ballast drives the (in your case DEAD)bulbs. It is essentially trying to start a dead bulb, causing strain on it.

IMHO don't turn your fixture on until you have the two bulbs (yes replace them both).


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## Fujo (Apr 15, 2012)

Yikes, I didn't know it was that serious. I did run it a couple more days with the dim bulbs, but I replaces both bulbs two nights ago now. It looks great again, thanks for the input.


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