Who told us to change MH bulbs once a year?

[Mark Spencer]

I recently changed the 3 250 watt metal halide bulbs in my Aquaspacelight after one year in service. I had noticed a hair algae bloom over the last two months and one acropora suffered RTN — all signs of aging MH bulbs that I had read about.
I am a photographer so I was curious about the change in illumination between one year bulbs and new ones. I measured the intensity of the old MH bulbs using a light meter at the surface of the water. I was only interested in relative intensities so I didn't convert the meter measurements to lumens. I measured f/16.5 @ 1/60 second for ISO 100. After I changed bulbs I measured the intensity to be 16.7 also @ 1/60 second for ISO 100, for a roughly 20% increase in intensity. I had expected the increase to be much greater.
I understand that we need to look at the spectral composition of the lights to compare the effective illumination levels accurately and that I didn't do that. Nonetheless this rough data begs the question: Where did we get the rule that we should change our bulbs every year? Is there some hard data in the form of spectral diagrams that show how bulbs age? Have there been controlled experiments that demonstrate the deleterious effects of aging bulbs?
People who spend $400 a year on bulbs want to know!
Mark Spencer

[GregM779]

You also need to consider the 100hr burn in time of the new bulb.

[Chaotic Reefer4u]

WOW, Mark Spencer, You Sound Very Edumacated With Your Saavy Well Spoken Speech There! "Count Me In" I Wanna Know Also About This Changing Light Bulb's Each Year Clich'e.....Mark I Would Like To Commend You On Doing That Very Well Needed Research! I'll Bet This Is Gonna Be A Good Thread!

[CrystalAZ]

WOW, Mark Spencer, You Sound Very Edumacated With Your Saavy Well Spoken Speech There! "Count Me In" I Wanna Know Also About This Changing Light Bulb's Each Year Clich'e.....Mark I Would Like To Commend You On Doing That Very Well Needed Research! I'll Bet This Is Gonna Be A Good Thread!

What The Heck Is With The Capital Letters On Every Word? That's Just Weird.



Anyway, I am interested - did your hair algae subside after changing the bulbs, or is it too soon to tell?

Thanks,

Crystal

[deansreef]

i am jumping in on this thread also.

[grim]

When I used Iwasakis, I didn't change them at all, I'm talking 2+ years on a bulb without issue. I still have all my old Iwasakis, I use them in the garage, they still burn great some 6 years later.

jb

[phergus_25]

most likely with the lower kelvin they burn longer. From what i understand the kelvin color changes not the intinsity that much, but i'm not the most informed about this stuff. So i'm tagging along since my bulb is about 7 months oid.
-greg

[LobsterOfJustice]

Our club recently had Sanjay Joshi come and speak and he said that bulbs DO NOT shift spectrum, they only lose intensity.

[Mark Spencer]

I also checked on lifespans of metal halide bulbs—12,000 hours. If your bulbs burn for 10 hours a day that's 1200 days or 3 years and 3 months! I understand that the bulbs will change their spectral output and decrease in intensity over time and that one would not use them for their full lifetime. Nonetheless it still seams premature to throw them out after one year or, worse, 9 months as many recommend.
Someone give us the data and show me I'm all wet!

[jamal-188]

I'd like to know as well..... it's been a little under a year on two of my bulbs and I really don't want to spend more money on bulbs.

[dendronepthya]

Mark,
You have pretty much hit on the same thing I have noticed with my own lights (Aquaspacelight as well). I actually measure PAR (PPFD) with an Apogee Quantum meter, and can confidently say that these bulbs last many years. The ones on my home system have lasted me close to 4 years now with no replacement and are still putting out enough light to keep any coral.

[samsfishnchips]

Mark Spencer, good question,

LobsterOfJustice, sounds great

it might come out just like uv lights, over time, less intensity, but still killing light,

it would be great to be able to keep the light longer, right now using three bulbs, and it sucks when changing time comes by,

only other thing I might add, would be carefulness with the change, since the new bulb would have higher intensity, that might shock corals, so less hours or window screen sheets would be a great idea to use,

sam

[Orochimaru]

Just tagging along.

[percula99]

Good point Mark Spencer. Changing bulbs is very subjective. A popular practice right now is to shorten the photoperiod. Some people are running MH for 4-5 hours a day. Why should they change lights once a year when someone running 12 hours a day is supposed to do the same. I want to keep an eye on this thread as well.

[Mark Spencer]

Looks like we have a good thread going. Crystal, I just changed the bulbs so it will take at least two weeks to determine if the light change made a difference. I will also check on my acropora that started showing RTN. In response to the break-in comment (100 hours): I will remeasure the light intensity and report back if it increases. Already I have measured another 0.1 f stop increase.
I'll bet Sanjay Joshi can give us quantitative data in the form of spectra on this question. I hope he reads this. I wish I had a quarter for every post that claimed changing lights after 9 months solved a serious problem.
Mark

[mikeshook]

I too like the idea of running the Halides for a 4-5 hour photoperiod....mostly during the time I am home from work, and running VHO while I'm gone. Less heat, less energy, less money.

[ReefSurge]

I'm curious also on the subject. Also are we talking of just MHs or does this include VHOs? I'm starting to have some algae issues and want to know if my 10 month VHOs are causing it or is it my 10 month MHs.

[Shark Bait100]

tagging, great subject

[Ereefic]

I believe it was the bulb manufacturers that recommend changing them out yearly.

I just don't buy the whole 'change them every 12 months' rule. I ran my ushios for about 18 months before changing to a different bulb. Never any problems with them.

I doubt the light is the cause for your algea issues Mark, excess nutrients is my guess.

[blueplanet]

Mark, good thread. I m in. certainly curious too. How's your algae bloom?

[Ereefic]

Originally posted by ReefSurge
I'm starting to have some algae issues and want to know if my 10 month VHOs are causing it or is it my 10 month MHs.

Could it perhaps be the 10 month old tank has been accululating nutrients and is just now showing signs of it and not the bulbs at all?

[GregM779]

I actually recieved a brand new 10k bulb from coralife last Friday. The previous one had lost some gasses and was turning yellow. They replaced it no questions asked while still under warranty, great service.
Anyways, the picture below is of the new bulb the day after it was put in, much duller and bluer than the others, at first I thought it was a 14k bulb. I contacted coralife and they said to let them know if it isn't the same after 100hrs. The difference is amazing, those are all the same bulbs.
I would also like to figure out hours to replace a bulb rather than saying years because as said above everyone runs them differently. I used to run 10hrs a day but have switched down to 5-6 hrs a day because of advice from a fellow reefer. The colors in my corals are really starting to improve.

[Mark Spencer]

It's amazing worldwide productivity hasn't plummeted. Look how many of us are responding to these forums during work hours!
My first tank, which had power compact fluorescent bulbs only, was plaqued with hair algae and I never got the better of it. When I upgraded to my current tank I changed everything, including a refugium, and I never had an algae problem.... until last month. So I can't say whether or not the change to MH bulbs made the difference (though the LFS owner was sure it was). May recent hair algae growth may be a nutrient problem. I am going to be careful NOT to change any other variables over the next two weeks to see if changing the bulbs has any effect.
I do know that, in fresh water planted tanks, algae has a competitive edge over plants in the blue end of the spectrum so one has to be careful to keep the color temperature down to app. 6500 K. If bulbs do change their spectral output over time I would think that the color temperature would go to the warm end. That's because deposits on the inside of the bulb would yellow the bulb. This happens in flash tubes in my studio. Same might be true of VHO's. But that's just a guess. We would need to know that information plus the absorption by algae as a function of wavelength to determine the effect of aging bulbs on algae growth.
Lots of questions. Who has an answer?

[thrlride]

That's a huge difference! Keep us posted on that one.

I find it hard to believe a one year old bulb will cause algae issues. I know it is written all the time but if there are no nutrients in the water then the algae simply cannot grow.

[GregM779]

It is amazing how many people respond during the day, I'm self-employed but still have to go to jobs, I'm sure I'll be late for my first one today.
About the algae thing why do we use lower Kelvin bulbs in our refugium to grow algae if it is the blue hue that they like? Is macro considered a plant and therefore giving it the advantage. I also notice less algae in higher K systems. I don't know if it has anything to do with the light but I've seen a lot less algae in 20k systems than 10ks.