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K rating on bulbs and Plants.

Discussion in 'Lighting' started by PlantedFishGeek, Sep 23, 2008.

  1. VaughnH

    VaughnH Lifetime Charter Member
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    It is the amount of light you use that determines just about everything else for the tank. If you have X watts per gallon for a standard geometry tank, that dictates that you need to use pressurized CO2 and good fertilizing. If you want to do without the CO2 you need to reduce the light to Y watts per gallon maximum. If you decide to use Excel, you can go a bit higher than Y watts per gallon, but not up to X watts per gallon.

    This is because it is light that drives the growth rate of the plants, and it is that growth rate that dictates the concentrations of nutrients that you need to keep in the water, including a carbon source. When you have more light intensity than you have nutrients available to support, you don't get the healthy growing plants that are needed to discourage algae from starting to grow.

    If 2 watts per gallon dictates using CO2, then if you don't use CO2 you need to reduce the light intensity. Does all of that make any sense?

    A contrary viewpoint is that you can acclimate the plants to grow well with lower levels of nutrients for a given amount of light, but you have to be willing to suffer through some algae problems as they acclimate. I haven't tried this, but those who like the leaner fertilizing methods, like PPS or Pfertz, insist it works well.
     
  2. crystalview

    crystalview Guru Class Expert

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    Yes Vaughn that made sense.
    I will have to go read PPS and Pfertz dosing.
    I am also looking into varying the amount of photo time for my better viewing, without the side effects of a higher light tank. Or using two lights. One for viewing and one for better growth but staying at the non CO2 level at various hours. It would be nice to be able to run a low light all day (12hrs) but not sure how to factor the what that change would bring.
     
  3. ceg4048

    ceg4048 Lifetime Charter Member
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    Well, it's not a matter of not wanting to use the red end. Your point was that according to the photosynthesis rate curve one should select the frequency producing highest growth. I was simply pointing out that the highest point on the curve is at or around 420 so that using this logic theoretically you should have highest possible growth using the actinic alone which peaks at 420nm. The fact is that you can use the red but also that you can use every other color as well even though they are not as high on the curve.


    I'm not so sure about that. I've used the Triton bulbs and the only thing that exploded was my wallet.:(

    Could the increased growth rate possibly be explained in part by the replacement of old bulbs with new bulbs which were simply brighter? There are certainly a lot of variables. How about starting out with the designer bulbs and then swapping over to the common bulbs. Was there a dramatic decrease in growth rate?


    Well I agree it's better to be energy wise, but it might also be just as well to get maximum growth for minimum outlay of cash. A common Sylvania or Osrram 55W CF bulb for example can be had for £3.75 whereas a Triton will set you back over £20. How efficient is that? Will your plants grow 4 times faster? Doubtful.

    Yes, I mean..this is exactly my point. This bulb is used to some extent in almost every office building and warehouse in UK (and maybe even in Europe). It's as common as dirt. Yet it grows any plant I want just fine. How much electricity do I have to burn to make up the £16 ($30) difference in bulb price? Sorry mate, from an economic standpoint that's a "Fail".

    Because the tanks looks almost as yellow as when illuminated by the 840. My point is that the plants will also grow just fine using nothing but incandescent lighting which, correct me if I'm wrong, emits mostly in the Orange/Red wavelengths.

    If a hobbyist lives in an area of the world that does not have access to fancy "plant" lighting, or does not have the means to afford designer lighting then he needn't worry. Any bulb used will grow his plant's and he needn't be concerned in the least. This is really the bottom line analysis.

    Cheers,
     
  4. defdac

    defdac Lifetime Members
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    Yes we agree. I myself have walked the line with a tad more wattage and bulbs with the best colors to be able to photography my tank more easily.

    But the point I would like to make is that you *can* optimize the spectral output and efficiency if you're reluctant to add more watts. Most important are very good reflectors of course, but you can walk the extra mile and also look at the PUR-efficiency.

    That is almost the same point as to why to choose flourescents over filament/halogen bulbs - despite the huge initial cost difference.

    I wouldn't talk as warmly about the triphosphor bulbs that emits alot of usable blue and red if it wouldn't be for their other benefit of lasting so much longer than fancier phosphor combinations where you have to change the bulb more often. It seems they can convert the electriciy so much better to usable radiation compared to many others and you can run them until they totally fail - and then they have at most 10-15% less intensity than a new bulb.
     
  5. Hilde

    Hilde Junior Poster

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    I disagree with this because of my experience with plant bulbs that I bought at wall-mart. I had 1 Philips 1-20 watt daylight bulb and 2 - 20 watt plant bulbs from wall-mart over my 29 gallon tank. The plant growth was very spindly. Since I swithced to a T5 bulb 65 Watt Dual 6700K /10000K by SunPaq the plants are growing better.

    I have been reading about lights and getting more confused as I read. For there are specs. like the wpg and kelvin that aren't consistent.

    The WPG rule is 2WPG of T12 lighting. IMO T5HO will give the equivalent of double this rule. WPG is the intensity of the light. Thus 2 - 20 watt over a 10 gallon tank only give 10wpg.

    The Kelvin color designation of a particular bulb is not always true to the black body locus line on a CIE Chromaticity map. Thus some 5000K bulbs look yellow and others white,especially when trying to compare a linear fluorescent with a CF or MH. This is where Kelvin ratings of bulbs can fall prey to marketing schemes/hype.

    I wish there was 1 spec I could look for to decide which bulbs are good to get the plants to grow. For when the bulb dies I don't want to buy another 1, for it cost $30.
     
  6. Tom Barr

    Tom Barr Founder
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    As far as what was said about the K rating not mattering, it's more a choice of aesthetic color choice by yourself, not growth of plants.

    Then the normal cheap cool FL's work as well as the designer bulb color mixes if growth is the variable measured.

    Aesthetics you can measure in other, more social scientific methods.
    But as far as growth, they are in fact the same as far as the studies that have been comparing the two.

    So pick a bulb that has a nice appealing color to your eyes/your senses.
    But do not fall for the claim about better growth, less algae and the rest........

    If you want real pretty reds, just buy Tom Barr's "Red Plant Paint" and get a brush. I gar-untee it'll make your plants red:p

    Regards,
    Tom Barr
     
  7. VaughnH

    VaughnH Lifetime Charter Member
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    I thought about suggesting someone try dosing the tank with beet juice, but I decided not to mention it here.
     
  8. defdac

    defdac Lifetime Members
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    So very very true.

    I use two different ways of calculating the kelvin temperature from the spectral distribution, the Robertsons algorithm and a polynomial variant developed by U.S. Naval Meteorology and Oceanography Command. They give about the same values for the range of Kelvin values we use in aquaristics, and they're often not what the manufacters specify.

    That said the colors doesn't have to be exactly ON the locust:
    Image:planckianLocus.png - Wikipedia, the free encyclopedia
    As you can see the the marks on the locust are very broad so one kelvin value actually can be a rather big range of different colors.

    That is why the kelvin measure also is rather useless. You don't know what color you get just by stating the kelvin measure.

    This get very obvious when developing RAW-photographs with for example Adobe Camera Raw. You have the Kelvin temperature-slider but also the green-red tint slider that will adjust the CIE Chromaticity point away from the locust. =)
     
  9. Tom Barr

    Tom Barr Founder
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    As the subject often gets way over many aquarists and the Public's head, marketing seeks to take advantage (Unwittingly, or in full knowledge) of this lack of knowledge, they use lots of jargon, do not ask the right questions, make false claims with no support(actually the opposite) and keep getting away with it.

    This is quackery in the market place.

    At least they are not adding fertilizer to Chocolate or milk. Not nearly as bad, but similar.

    Fragrance is unregulated and they do no test on these in beauty products. Really amazing, but unless someone does something, disproves them based on sound science, this crap keeps coming.

    Takes longer to disprove than it does to come up with yet another snake oil.
    Spend some $ in R&D and long term business goals, not quarterly marketing goals. The quick $ vs wise long term.

    Light bulb companies will say all sorts of things to get you to try and buy, you know there is no regulation, but many wander off, think the companies are really on to some "new research" and plant growth/photosynthesis.
    No, a plant scientist is going to know more about what makes a plant grow and how to measure that.

    Show me the dry weight differences, with error bars under controlled methods for the species claimed. Otherwise, shut the heck up.




    regards,
    Tom Barr
     
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