When to replace your MH/T5/VHO/PC?

[iSpeakWhale]

Andy,

Thank you for you input!!! This is the kind of input I was looking for.

I think the only thing you've left out are PC. How long do they last anyway?

 

[LittleBlueGT]

I have very little facts to back this up but, I believe there is truth to flourescents changing spectrum over time.

Have you ever looked at two of the exact bulbs, side by side, one old one new? They look significantly different, in fact many would swear they are differetn colors.

Why?

My theory:

The phosphoros themselves do not change in a bulb over time. Have you ever noticed that most flourescent lamps have a very pronounced peak at a certain wavelength? What happens is the peak (usually around 420 to 480Nm) is what degrades the most over time. Then the percentage of light changes. For example a lamp may have 80% of its energy around 420Nm and it looks like an actinic bulb, as the lamp degrades the 420 peak degrades the most, then the lamp has maybe 60% of its peak in the 420 Nm range. Thus the bulb looks more yellow.

I believe there is some truth to what people on both sides of the story have to say. But to really understand it one has to have an unbiased in depth understanding of htese lamps age.

 

[LittleBlueGT]

Nobody has any opinions on this?


Really?

 

[ASH]

From IceCap:
Re the PC estimate on useful life I'd have to ballpark it around 1 year. The problem is there are so many brands of various quality, ballast options and venting of heat. It's not like the days when they all came from Panasonic. The lack of a good lampholder boot that's watertight is cause enough to select another option.

The worst case is when I see a PC in the same housing as a MH bulb. Unless the heat is isolated (good luck) the PC has to suffer.

Andy

 

[tgunn]

I have very little facts to back this up but, I believe there is truth to flourescents changing spectrum over time.

Have you ever looked at two of the exact bulbs, side by side, one old one new? They look significantly different, in fact many would swear they are differetn colors.

Why?

My theory:

The phosphoros themselves do not change in a bulb over time. Have you ever noticed that most flourescent lamps have a very pronounced peak at a certain wavelength? What happens is the peak (usually around 420 to 480Nm) is what degrades the most over time. Then the percentage of light changes. For example a lamp may have 80% of its energy around 420Nm and it looks like an actinic bulb, as the lamp degrades the 420 peak degrades the most, then the lamp has maybe 60% of its peak in the 420 Nm range. Thus the bulb looks more yellow.

I believe there is some truth to what people on both sides of the story have to say. But to really understand it one has to have an unbiased in depth understanding of htese lamps age.

Okay, I think I'll take a stab at it.

From what I've read, fluorescent tubes typically have very spikey spectral distributions because the mix of phosphor coatings in the light preduce somewhat specific spectrums of light.

If we assume that all of the phosphors were to degrade at the same rate in the tube, then the entire spectrum of the lamp would degrade as the lamp ages, resulting in an overall dimming of the lamp without a color shift.

However, if we assume that certain phosphors in the mix degrade differently over time, then I think a spectrum shift might be possible.

I'm not the most knowledgeable source of fluorescent tubes and how they're made, but perhaps someone else out there could shed some more light on the topic?

Tyler

 

[LunarCubes]

Im curious what the useable life of a MH bulb (Hamilton 14K) would be for a FOWLR tank? Since there are no corals that specifically need the light to thrive (although Im gonna throw some shrooms and possibly other softies in there), would it be ok to run them past there "useable life"? I have heard old bulbs cause algae blooms but if Im running rowa-phos 24/7 with 0 phosphates would algae really be a problem? Im wondering if I could run them for like 2 years? maybe?

 

[scottfarcuz]

Im curious if others also belive that old bulbs cause algae? I recently started a thread asking exactly this and all that replied seemed to think this was a myth...

Plese reply there and here to help inform others if you can.
http://reefcentral.com/forums/showthread.php?s=&threadid=517130

 

[LunarCubes]

bump

 

[ASH]

From IceCap:
LunarCubes -
I'd run them on an electronic ballast until the ballast determined the bulbs are at end of life and it shut down instead of lighting them.
On a conventional ballast, two years seems reasonable to expect.
Threat of algae problem in this case would be slim to none.

Andy

 

[shelburn61]

<a href=showthread.php?s=&postid=4038069#post4038069 target=_blank>Originally posted</a> by ASH
From IceCap:

#1 VHO was infamous for 6 to 9 months of 80% plus output before a sharp drop off. That is the result of using a billboard type conventional ballast which is hard on the lamp when starting and during operation.

#2 For most [MH] bulbs I would suggest 14 - 18 months. More for an Iwasaki bulb, less for some of the less expensive new imports. MH bulbs do shift color over time and if they're under or over powered will give off different Kelvin characteristics then they were specified to provide.

I'm sure I left a lot out but feel free to follow up.
Andy

#1 How do I tell whether I have a "billboard" VHO ballast?
#2 Will this apply for the new Iwasaki 14k as well?

 

[ASH]

Billboard VHO ballasts that weigh in around 10 lbs or more. Sometimes a lot more. They light and eat fluorescent lamps only.

The 175-watt 14K Iwasaki bulb is MH which we run at manufacturer's suggested output. As it is, it's very bright. I've upped my estimated bulb life when run on our electronic ballasts to two years over a reef.

Andy

 

[Brad Black]

Hey ash, thanks for the good info. Small world, I just e mailed your company a couple of hours agp about a similar subject. I bought a 100 gal reef set up complete (used). It contains both hard and soft corals as well as fish. The lighting set up is as follows:Ice Cap 660-009 electronic light driver, 2- "super actinics", 1- "aqua sun", and 1-"actinic white"- 110 w ea, they are all T-12 VHO's. The problem:with the current setup all of the lights come on together. I would like to stagger the start times of the blues and the whites as many talk about (actinics first then whites then actinics turn off last). I also have heard about dimmers to ease the tank into daylight which I would like to do. So I have two questions: 1) do I need a second ballast or can I reconfigure the 660 to power the two sets at different times 2) are the lights I am using sufficient for a mixed tank ( may add clams eventually)?
Also can you recommend the items I will need? If you get a min drop me a PM or thread...Thanks much-look forward to hearing.
Brad B.

 

[ASH]

I'd go with the existing system till it's time to relamp. Then depending on your light needs I'd upgrade to T-5 HO lamps with SLR, consider adding a pair of the new 175-watt 14K Iwasaki MH bulbs and if you want an early and late day lighting, try ReefGeek.com for one of our DY ballasts. You can run one or two 46" 54-watt T-5 HO lamps. Make them super actinics (UV's new line should be out by then f/k/a URI) and you have at a reasonable price a state of the art lighting.

Re the all at once start time now, it's likely more an issue for you than the tank's inhabitants.

Andy

 

[Scooterman67]

<a href=showthread.php?s=&postid=4051821#post4051821 target=_blank>Originally posted</a> by tgunn
Okay, I think I'll take a stab at it.

From what I've read, fluorescent tubes typically have very spikey spectral distributions because the mix of phosphor coatings in the light preduce somewhat specific spectrums of light.

If we assume that all of the phosphors were to degrade at the same rate in the tube, then the entire spectrum of the lamp would degrade as the lamp ages, resulting in an overall dimming of the lamp without a color shift.

However, if we assume that certain phosphors in the mix degrade differently over time, then I think a spectrum shift might be possible.

I'm not the most knowledgeable source of fluorescent tubes and how they're made, but perhaps someone else out there could shed some more light on the topic?

Tyler

I have to believe there is a spectral shift & not on an equal basis, we need actual test to prove this not just someone’s word (Experts) that this isn't true with newer H.O. T5's, I think overdriven they will shift rather quickly, until I see the actual proof I would find it hard to believe a good sales pitch. JMOFE!

http://www.reefgeek.com/products/categories/lighting/104048.html