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Thread: Wavelength-specific intensity drop for flourescents?

  1. #16
    Clownfish

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    Boomer, I am interested in how you arrived at your conclusion that flourescent bulbs should be replaced after 6 months? How much of a spectral shift are we talking at 6 months? What might it be like at a year?

    I tried searching here and rc for some data but have been unable to find anyone whos tested it.

  2. #17
    Clownfish

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    So far I have found several people that change out their t5's every 6-8 months. I have not found any data yet as to why thy do this other then they "see" a difference at that point, which I dont really trust as a valid scientific explanation.
    There was also a totm on rc that ran his for 16 months without "seeing" a problem.
    Then there was this post by the president of IC:
    http://www.reefcentral.com/forums/sh...t&pagenumber=3
    The more I research the more confused I get.

  3. #18
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    T5HO GE 54-watter on an T5HO ballast will last up to 20K hours. For reef applications, 3 years approx. The 6 - 8 month rule only applies if you're roasting your fluorescent lamps (or selling lamps). It was once true of VHO lamps with cheap, conventional billboard application ballasts. In 6 - 9 months they could lose 30% of initial output.

    New lamps will always appear brighter and other than new T5HO type lamps, they lose 10% in the 1st 100 hours of use. Add to that, when swapping lamps you start with a salt free lamp and clean reflectors.

    Andy
    That is from Any @ Ice-Cap, but I don't see any test or proof of that either, I did see test done on VHO's on a good set-up & they suck after 6 months but you Can't See that, you have to test that but again I can't find it, mainly because most people use MH they don't spend the money on much other testing to prove any better, not from what I've seen but I could be wrong with that..

  4. #19
    Clownfish

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    Heres another post from IC pres:
    "From IceCap:
    I was invited to respond and glad to have the opportunity to silence some rumors.

    The prior post regarding new VHO's (or any T-12 lamp) is in error. Fluorescent lamps other than the new T-5 HO's, all lose 10% of initial output in the first 100 hours of operation (and at that point output is considered 100%). After that they slowly lose output and will remain above 85% of specified output for two years when run by our electronic ballasts. (BTW, they don't shift colors as they age.)

    Most of the short life estimates above were true at one time, but things change. 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. We use high frequency to get results and a ballast that adjusts to the load. Heat is also a factor on fluorescent lamp life. If the ambient temperature around a lamp is 150F or more you will lose output and lamp life. T-5's again are the only exception and can tolerate higher operating temperatures. The heat issue is why PCs are a bad design for a fluorescent lamp. Besides the fact that the design cuts down on the ability to direct light where you want it, one half of the lamp cooks the other side. Other factors are proper endcap installation for sound connections between the endcap and the lamp's bi-pins. I recommend relamping every 18 - 24 months when using good VHO lamps and our ballasts. Even though super actinics lose output faster, the amount of light at that end of the spectrum is so over the top, that you could use them till they don't phosphoresce to your liking and forget about the lamp's age. With overdriving NO lamps (T-12 & T-8) I recommend 12 months.

    T-5 HO lamps are not an unbent PC, they are a new technology. I've tested GE 6.5K lamps for the equivalent of 2 years on a reef tank with improper venting of heat and still found you were getting above 90% after 24 months, being overdriven on our VHO ballasts (a 54-watt lamp runs at 85-watts). On a T-5 HO ballast, 3 - 4 years is doable. Don't run these lamps on a ballast that doesn't shut down power to a dead lamp. Also there are many brands of T-5 HO lamps and we'll have to learn what's good and what's not.

    MH is a bit more messy but using electronic ballasts lowers the initial starting voltage and if it's a high frequency ballast, eliminates the constant on/off of the bulb's arc. Those are the main factors of MH bulb life. Heat is not a factor. In fact they thrive in a hot environment (the bulbs, not the ballasts). For most 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

    "
    Thread:
    http://www.reefcentral.com/forums/sh...trum+AND+shift

  5. #20
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    I think I'll get an ear full but I had to agree with this, I have to think until we see the actual test results, what they say is good for 2 or 3 years is way too much.

    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

  6. #21
    Clownfish

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    heres antoher post by Andy regarding spectrum shift in flouro's:
    "
    Regarding spectrum shifting, this is a phenomena that occurs with most MH lamps and only the most worthless of fluorescent lamps. The output will drop but shifting color would mean the phosphorus coating was applied in layers which burn off in sequence producing different looks as it ages. The only fluorescent lamp I've seen shift is a lamp with a pin-hole that allowed gases inside to escape. When this occurs the lamps look pink to washed out red, and they stop working in a day or two.

    Andy
    "

  7. #22
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    Andy is a good salesman, until I see him put up the facts & testing data; what he says is about the same as me saying cow can fly!

  8. #23
    Clownfish

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    No its not the same, because your no expert on flying cows(or maybe you are, but its not in your signature! =P). Andy however is the president of one of the most popular lighting manufacturers in the aquarium(edit) industry. They sell MH as well so he has nothing to gain by bashing either.

    In lieu of any data, I am more inclined to believe him. If a t5 becomes useless at 6 months, then how come people report going 12-18 months between changes? Obviously this isn't the case. If the bulbs had lost so much after 6 months, they should be putting out close to nothing by 18 months.

    Im not advocating that you run your t5's for 18 months, but if 18 months is ok, then 12 should be more then fine.
    Last edited by jezzeaepi; 09-27-2006 at 03:53 AM.

  9. #24
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    Nope I don't know anything about flying cows. I know who he is & to some point I agree the T5's are the best fluorescents our there yet for out hobby. We did see a few guys growing sps with them but the growth would slow down very noticeably after 6 months, It was from a few European guys I think. That has to tell me something about them, also they were top of the line equipment, even though I know they continue to improve on everything daily. Do a search on T5's you will find him maybe, that is data we can see because he is doing it real time. All I want is for Andy to show us the actual data, that is it & then I would get to see the results for myself & make my own opinion on the matter.

  10. #25
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    Andy however is the president of one of the most popular lighting manufacturers in the industry.

    You mean in the aquarium industry not the lighting industry.

    All fluorescents shift it is a matter of physics, power lose and the chemistry of the phosphors. You have to remember what they do, cause a shift in wave length by changing short UV light in longer visible light. Different phosphors have slightly different energy requirements and as the lamp ages there is a loss in output. That loss not only lowers the amount of energy but produces less heat causing the lamps to shift to more to the red and this is without the phosphors degrading at different rates. The issue is that fluorescents just have less of a color shift with T-5's being the least. Color shifting is evident by seeing the color shift in fluorescent lamps with dimmers. Just increasing the ambient air temp around fluorescents causes some serious shifts, especially those housed in MH fixtures and to include overdriving the lamps. So, I also agree with Tyler. All one has to do is a Goolge search on color shifting in fluorescent lamps or look at ome of the technical manuals or NLPIP and LRC
    Last edited by Boomer; 09-27-2006 at 01:17 AM.
    Boomer

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  11. #26
    Clownfish

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    *edting done*

    http://www.lrc.rpi.edu/programs/nlpi...rStability.asp

    There are two graphs on this page.
    The first shows the color shift after 2400 hours in a CFL. One manufacturer had virtually no shift in spectrum, while the other had a fairly large shift. This seems to support the idea that buying better bulbs will insure a longer time before shifts. Manufacturer B showed almost no shift after 2400 hours.

    The next graph shows MH's with 8000hr of use on them. They seem to have shifted almost twice as much. They also state that MH's have a GREATER shift in color over their life.

    Althoguh they are testing two different lengths of time(2400 vs 8000), both times are 40% of the bulbs rated life. Im no expert in lighting, but if this can be extrapolated out to t5's whos rated life number in 20k(the same as MH) then I dont see why the color shift would occur any differently.

    Peace,
    Jesse
    Last edited by jezzeaepi; 09-27-2006 at 07:43 PM.

  12. #27
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    That would be correct All fluorescents shift less than a MH. I have not seen or looked for a T-5 yet.

    You see that blue circle. That is called the Oval Window. All lamps have one and the lamps K is a function of that spot. On any lamp there is suppose to be a specific matahamaticlly calculated Oval Window. It is that OW where the K value comes from. I'm sure you have heard the terms 10K MH and True 10K MH. That is because some companies are trying to scam you and go outside the Oval Window and use a spot outside the OW as their K value, which is really a false K value. I have only seen that done in this hobby

    It is nice to see you go look on your own It was a hint to go to either NLPIP and LRC......and you did

    Something else you may find. Any bulb only puts out about 20 % of its W rating. A NO 40 W only puts out about 10 W of light, a 400W MH about 100W of light.
    Last edited by Boomer; 09-27-2006 at 07:39 PM.
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  13. #28
    Clownfish

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    Are there any companies that you recomend for aquarium lighting(i.e. one that has TRUE K)? If they tend to lie about their actual k output, then hows an aquarists to know what they are actually getting? Darn companies and their tricks.

  14. #29
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    I guess that is where the heat comes in right?

  15. #30
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    jezz

    It is only one or two companies and it is those dealing with MH. What are you looking for ?

    but if this can be extrapolated out to t5's whos rated life number in 20k(the same as MH) then I dont see why the color shift would occur any differently

    Yes but it just does not end up that way. T-5's are not std fluorescents or CFL .VHO have a large color shift and short life. T-6's are said to have no color shift at all.

    I just found this from a lighing company

    NO COLOR SHIFT
    T5 lamps produce an even, consistent, high quality light that is the same from fixture to fixture, and does not change over time.



    more stuff here

    http://www.aboutlightingcontrols.org...-low-bay.shtml



    Scoot

    You lost me on the heat. They just pick a spot on the bulb where the K is higher. The K is measured at specifiic spot or is suppose to be. The OW is more of a probelm with MH and giving false K due to then internal structure and how the light leaves the plasma arch tube
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