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Definitive answer on PAR differences between T5HO, T5NO, T8, T12?

Discussion in 'Lighting' started by kelleyc, Aug 18, 2010.

  1. kelleyc

    kelleyc Junior Poster

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    Hi all,

    I'm new here, but have been lurking around for quite a few years.

    I've spent quite a bit of time reading across forums including this one, specifically to find a definitive benchmark of PAR levels across different lighting systems (with all other variables constant), but with so may opinions out there, I'm left even more unsure than when I started!.

    So, essentially, my question requires someone who has a light meter, and has actually taken comparative measurements...

    the question is:

    Does 100W of T5HO lights provide higher PAR values (at a fixed distance of say, 12") compared to 100W of T12 lights?

    This assumes that all other variables are the same (reflectors, tank size, distance to substrate, ballasts, distance to water surface, bulb brands, fixtures etc...)

    If the answer is yes, is there a rough benchmark percentage of by how much? 10% more, 15% more?

    I understand that in the real world, all the other variables cannot realistically be the same (brand of bulb, operating temperatures, ballasts, water clarity even!), but let's pretend! ;)

    Going further, has anyone measured the differences with other lighting types as well, using t12 as the baseline reference – T8's, T5NO's?
     
  2. Oreo

    Oreo Guru Class Expert

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  3. kelleyc

    kelleyc Junior Poster

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    Hi Oreo,

    As far as I can tell, that thread refers to a work in progress database of sorts...

    I don't think there's any rough conclusions that can be drawn out of that thread yet... ?
     
  4. SuperColey1

    SuperColey1 Guru Class Expert

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    OK TO answer your question:

    In general terms Yes 100W will give higher PAR than 100W of T12. However that doesn't mean the whole tank is recieving mhiger PAR.

    You see most people look at light in terms of its output. What we want to know is its delivery. Yes we know it puts out X amount of PAR but how much is it at the substrate directly below, an inch from directly below and so on.

    In essence yes T5 will be betterdirectly below but other lighting may be better for spread. We don't want superhigh PAR over the direct centre of the tank and super low PAR at the edges of the tank. We want as equal a measure all over so whilst the T5 may produce the higher PAR below. The T12 setup may provide a more 'level playing field)

    To coin a phrase commonly used on here 'Its a trade off'

    Personally when someone asks me what light I would suggest I tell them T8 on electronic starters. Why? Becuse it means less light per tube but you need more of them. therefore directly below is not super hot and becuase there are more of them the spread is btter.

    AC
     
  5. hbosman

    hbosman Guru Class Expert

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    This makes sense, especially now since we are getting away from the more PAR, the better, attitude. There is another trade off however. If you compare the prices of bulbs favored by planted tank people, the T8s are often close in price to the T5 HO bulbs so, if you need more T8s than T5 HOs, the overall cost might be higher. Also, T5 HOs can last 2 years vs. 1 year for the T8s.
     
  6. nipat

    nipat Guru Class Expert

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    Aren't T5 and T8 lifespan the same, regardless of HO or not?

    I used to think about switching from T8 to T5 for this hobby's electricity cost.
    But after finding they were just about 9% more efficient, I stopped.
    Especially when T5 AquaStar's are HO only.
     
  7. nipat

    nipat Guru Class Expert

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    I should have used the word ‘about the same’ (20000 vs 24000 hrs).
    I mainly use Philips 865's (with 1 AquaStar in the mix),
    so I meant to compare between T5 and T8 version of Philips 865.
    http://www.mueller-licht.de/Fluorescent_lamps_PHILIPS_OSRAM_T5_T8_L63.html
     
  8. hbosman

    hbosman Guru Class Expert

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    hmmm... The numbers I usually see for T5 HOs is 10,000 hours which would be over 2 years while I remember reading replacing T8's once a year. What was worse yet is CFLs needing replacing every 6 months. Odd thing, I thought CFLs and T5s are the same technology using the same ballests and all. I can tell you, I used to use 3x25 watt T8s and now I use 2x39 watt T5HOs and have paid about $15.00 each for comparable bulbs in T5 and T8s. Of course, I'm not comparing them to $20.00 Geisemanns which I also have.
     
  9. kelleyc

    kelleyc Junior Poster

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    Ok thanks for the answer SuperColey1.

    I understand the general basis that PAR is not the be all and end all of things - spread / distance drop off is critical when considering how the PAR is being delivered down into the tank.

    What I was looking for was a definitive 'starting' point (as definitive as you can get without a light meter!) as to wether watt for watt, t5HO's do produce more PAR (at the same distance/angle). I read some claims that t5ho's have less light per watt than t8s, and then confuse the whole subject even more by throwing in other variables like trying to use equal bulb lengths as comparison, etc... All those are valid of course, but it gets the discussion no where when there are no fixed constants to the basis of comparison. From visual observation I do notice that t5Ho's seem to have better light penetration, but have less spread.

    Thanks a bunch. Would you have any numbers as to roughly how much more PAR per watt T5Hos emit compared to T12s?
     
  10. Ekrindul

    Ekrindul Guru Class Expert

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    All in all I think, if there is no visible algae and there is healthy plant growth, you don't have too much light. Once you reach this point, you can move on to the next step. How much light can you wittle down to and still have healthy plants, since algae becomes almost a non-issue.

    So, with all the variables involved in the PAR readings (light spread, type of tube, open top or not, etc) when using them as a reference as opposed to having an actual probe in your tank, wouldn't it be far more efficient to reduce the lighting (removing a bulb, lifting the fixture) and observe the result since you would be working on faith using a reference anyway? The worst that could happen would be some sluggish growth, possibly some algae growth, both of which could be overcome by returning to previous setup and routines.

    This has been my thinking recently, as I don't see myself purchasing a PAR meter anytime soon.
     
  11. SuperColey1

    SuperColey1 Guru Class Expert

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    [
    If we look at it that way we could say the type of bulbs favoured are high output anyway because the majority are sitll of the thinking that newer technology, less tubes, more light etc is best. They miss the point. What we need to do is reverse their thinking and stop them thinking of what light the tube is giving out and more where is receiving the light

    T8 is much cheaper than T5HO. Especially if you buy 'normal' tubes instead of the ones with the letters A Q U A R I U M on them. In essence they use the word to push up the price. You can find the same (if not better) tubes for less without that word :)


    Nope other way round. T8 and T5 last the same as long as you are using electronic ballasts. T8 on older systems and many cheaper systems today are using magnetic 'flicker start' ballasts and it is the magnetic ballast that is making the tube wear out quicker. 1 year/2 year is way off research I have read. It is suggested that at 40% life (approx 8-12000 hours minimum) there is only 5% degredation of T8 and T5 (NO not HO) when used in conjunction with an electronic ballast (programmed start not instant start).

    T8HO and T5HO last less than their lower wattage counterparts plus the lower wattage 'NO-Normal output' lamps are more efficient and give more Lumens per watt (not that lumens are a measure we are interested in)

    Another problem with the HO/NO is that you can't use an NO in a HO fixture. When people thought they had 20W (T8HO) 24" on most older setups the ballast was an NO 18W. They gained nothing. May as well have been using the 18W NO in the first place!!!

     
    #11 SuperColey1, Aug 19, 2010
    Last edited by a moderator: Aug 19, 2010
  12. kelleyc

    kelleyc Junior Poster

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  13. hbosman

    hbosman Guru Class Expert

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    SuperColey1 perhaps at your location, T8s are cheaper. I've looked on hydroponics sites and the prices aren't much better. If I were using 48" bulbs, yeah I could go to Homedepot and get an $8.00 bulb but at 36", I have to get bulbs that say "Aquarium" on them. That's why I mentioned that T5HO's could be cheaper for the same wattage. T5NOs using more tubes with less wattage would probably give better spread for a given wattage but, they are again about the same cost per tube and they lose on lack of availability.

    I am currently using a lower cost fixture, Nova Extreme 4x39watt T5HO but with only the 2 outer bulbs lit. this gives me good growth and asthetics with minimal algae. I bought it thinking I needed the 4 bulbs. I found out the hard way, that was wrong.

    http://www.fosterandsmithaquatics.com/product/prod_display.cfm?c=3578+3733+8066+3814&pcatid=3814

    http://www.aquariumspecialty.com/catalog/product_info.php?cPath=28_39_448&products_id=2622&osCsid=b9bb42dca5f9881d7002c95022fa8b58

    Anyway, just my observations with what is available to me.
     
    #13 hbosman, Aug 20, 2010
    Last edited by a moderator: Aug 20, 2010
  14. SuperColey1

    SuperColey1 Guru Class Expert

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    I think I've confused you a little here. T5HOs do not have a lack of spread. compared to T8. That isn't what I am saying. what I am saying is that if you use T5HO then the much higher wattage means that you either have to blast the tank with light to gain the spread OR settle for less spread but stay at a reasonable level in terms of power. It is the number of point sources that improve the spread not the difference in tube.

    4 x T5 will be slightly better than 4 x T8 at the same wattage due to them being the best efficiency. However T5 seems to have been lost in the ever responsive world of technology and marketing. T5HO is the dominant tube in that category.

    What I am saying is if you are looking for say 2WPG over a tank and the choice was 2 x T5HO or 4 x T8NO then the 4 tubes would be better in terms of equal spread. Both the same WPG but the T5HO option give most of the light in a less uniform way.

    I can quite believe it. On another forum I was talking to someone r.e. upgrades and they didn't know what T8 was. they linked to Dr fosters and sure enough it is all CF and T5HO. I think the states has a problem here. In the UK I can source T8 pretty cheaply and because they are pretty common in office/warehouse lighting they are quite readily available and good prices. T5HO seems to have only taken off in aquariums over here. Bit of a parody really seeing as the office/warehouse could benefit from a little more light in my eyes where us in the planted setup at least could do with having the slightly les powered tube ;)

    Totally agree on the T5s. they are the most efficient flourescent tubes out there and you can't find them. People are pretty obsessed with more for less these days. Want more light from smaller uits. Want smaller phones etc. Its a pity that each item is not taken on merit for the purpose it is to be used for rather than just more light smaller space - Must be better :)

    As a side issue I got rid of the singing dancing internet and application laden MP3 capable iphone. Was a free upgrade but I just want a phone. Something that I can use as a phone and send the odd text. I replaced it with a Nokia 8210. 10 year old technology but super small and super cool (for me anyway.) Sometimes older technology is more suitable to the user than the latest all singing all dancing item.

    Yes T5HO is the best flourescent light but is it the best solution for the user's particular application. In our case no. In marine's case yes.

    AC
     
  15. kelleyc

    kelleyc Junior Poster

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    Aaah, ok. I did get a little confused.

    Coincidentally, even with the clarification, it's the same conclusion for me... here's why: I have a single 24w T5HO over my 2 ft tank, place about an inch over the water surface. The single tube as you rightly mentioned, coupled with the extremely close position above the tank, gave me a fairly uneven lighting spread. Compared to my older fixture (2 bulbs, T8s, sold it off), the spread was nice and decent.

    It did seem (purely from visual observation though), that the t5HO, while only a single tube compared to the old 2x t8s, does seem to have a narrower, if more penetrating, light. I vaguely recall once trying to take out one of the t8s and leave only a single tube in the fixture, and the spread still seemed nice and wide (if pretty dim). Hence the erroneous assumption.

    Kind of regretting getting the Hagen GLO T5HO double light fixture now though. I don't think I can run both tubes at a go without having major issues, and just running a single light seems to be a tad under lighted and not well spread out enough for my setup.

    Maybe I should just hang the fixture from the top and give it plenty of distance, allowing me to employ both tubes.
     
  16. csmith

    csmith Guest

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    I've got the same GLO 2x24w fixture over my 20H. Right now it sits 14" from the waters surface and a total 28.5" from the substrate. I'm still not quite sure it's high enough.

    I don't think you can call this "definitive" data as every fixture will have its own quirks, but it's good for rough estimates I'd assume. I've used it quite a bit.

    http://www.barrreport.com/showthread.php/6036-Massaged-PAR-Data-for-T5HO-lights
    http://www.plantedtank.net/forums/lighting/105774-par-vs-distance-t5-t12-pc.html
     
  17. kelleyc

    kelleyc Junior Poster

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    Thanks for the links csmith!

    Quite helpful.
     
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