# Replaced MH bulbs - WOW, what a difference!!!



## BryceM (Nov 6, 2005)

I've had my 180g tank up for about two years now. The main lighting is provided by three 150W HQI metal halide bulbs. It occurred to me recently that the bulbs were about 18 months old and were probably due to be changed. I swallowed the jagged pill and placed an order for new ADA 8,000k bulbs. They're even more expensive than they were before - ouch!!

I hooked them up today and the difference in light output is incredible. No wonder I've been having a harder time keeping HC healthy down by the substrate.

Does everyone agree that the lifespan of a MH bulb is usually about a year? I run mine for about 6 hourse per day so I figured they'd last a bit longer than average.

Is there any useful application for old but still-functional bulbs?


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## Jeff.:P:. (Nov 20, 2007)

Yea, I'd agree on a year or a little less. I'd say keep the bulbs as a back-up, you never know. Here's some great MH bulb info from our MH reef guy Sanjay. I know it's reef bulbs but some of the info can cross over.



> "The study presented some very interesting data on the life of metal halide lamps. It reinforced the view that the spectral qualities change over time resulting in the change of the CCT of the lamps to lower values due to reduction in output of the blue portions of the spectrum. In 2 of the lamps (XM, EVC) it also showed an unexpected increase in the PPFD output which can possibly be explained by the fact that there was also a corresponding increase in power consumed. This effect was not seen in the Giesmann Coral lamp, possibly due to the electronic ballasts being better at regulating the power draw. Another point to note was that the drop in output over almost 17 months of use was around 21%, lower than I would have expected. A similar study by Allen Chantelios [3] using seven 250W DE Phoenix 14000K with Icecap electronic ballasts shows a similar trend of gradual decay over time - of an average of 25% over 12 months. If the change in spectral output is not a big concern, these lamps can be used for much longer periods of time, especially if the fixtures can be lowered by a couple of inches to compensate for the loss in light output."


article:
http://www.advancedaquarist.com/2008/7/aafeature1


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## Ravenous (Aug 18, 2008)

http://www.highend.com/support/training/metalhalide.asp

This is a good link as well. It helps understand why and how the degradation occurs and the effects on not only the light output but also the impact on the spectrum.


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## trenac (Jul 16, 2004)

I'd say a year is about right, give or take a little. Also the brand being used makes a big big differnce in the brightness & look of the light being produced. I've found the Phoenix to be an exceptional bulb.


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## Bunbuku (Feb 10, 2008)

Hey Bryce did you get the "Green" version or the regular version? I have the regular 8000K in use since May x 6 hrs a day and looking to get a spare soon.


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## BryceM (Nov 6, 2005)

I got the 'green' this time since the Senske's were out of the regular bulb the day I ordered. There isn't that much of a difference, but I do like the color cast. I've got to seriously look at alternatives though given the ever-rising cost of the ADA bulbs.


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## bigstick120 (Mar 8, 2005)

I think its more the weak US dollar right now!



BryceM said:


> I got the 'green' this time since the Senske's were out of the regular bulb the day I ordered. There isn't that much of a difference, but I do like the color cast. I've got to seriously look at alternatives though given the ever-rising cost of the ADA bulbs.


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