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Re: [APD] Dreaded Lumens/PAR/PPFD/Watt per Gallon Topic
really. i'm gonna have to go have a talk with some professors. because
thats not what i learned at all. i learned that those measurments
currently are based on all light produced not just the human visual
spectrum unless you are strictly speaking of photography endeavors. that
the measurments for photography are different than those made for say
lab use but carry the same names for whatever weird reason. not saying
your wrong just stating what i was taught.
as to heat and such. true although when your talking plants UV is most
certainly not useless within the right type of UV. which isnt to say
that lamps dont waste light in the useless uv bands, but that uv in i
think only one band is very important to plant growth. and your right it
doesnt contribute to the heat factor, what i was trying to say and
apparently missed on, is this. Plants aside, and focusing on light only.
making light in the UV bands is still making light useful or not, but
for every degree of heat created thats energy not creating ANY light at
all. hence if you were using a an extremely inefficient fluro tube, just
for a hypthetical. they use phosphours and coatings to alter the
spectrum across the board, if the tube is creating excessive heat thats
a waste. maybe your getting 50% of the light you could get using more
effcient cooler bulbs. therefore on a light thats 175 watts and sets
things on fire when it touches them compared to a 175 watt cooler bulb
thats a ton more light at the same wattage.
i'm not saying WPG is completely useless either. but it isnt exactly
IMO, given facts like that, all that accurate. the ultimate point is
that not all watts are equal. hence the point that fluros at 20 watts
are worth at least 2 or 3 times that in light output at the same wattage
from an incadescent. as the ligthing technology increases so the WPG
rule becomes unable to make the same formula it did 10 years ago. soon
your going to be way off using that rule of thumb.
i agree about the photosynthesis action spectrum. if your not in it then
your wasting your time all together. and if you look to that spectrum it
does include some UV light i think UVA. i cant remember off hand which
is used by plants. as to PAR and Einsteins, i dont know as much about
them. it seems to me its been left to us to find a way to measure the
light intensity in the action spectrum so that we can determine more
accurately what should go where and how much so we arent wasting energy,
because quite honestly when you get to around 3 big planted tanks, your
talking a about a good conversation about the energy bill with the
missus, if you have one.
Wright Huntley wrote:
>>Date: Sat, 17 Sep 2005 00:05:22 -0600
>>From: urville <urville at peoplepc_com>
>>Subject: Re: [APD] Dreaded Lumens/PAR/PPFD/Watt per Gallon Topic
>>To: aquatic plants digest <aquatic-plants at actwin_com>
>>I never understood why the lumens and lux things never worked as well?
>>in fact everything i've read about lux and lumens seems to be based on
>>some archaic text i never saw when i was learning about them.
>>lux is a unit of measurment of the intensity of a light source reaching
>>any surface. in fact lux is the better deinfed as the measurement of
>>lumens per square meter. period.
>No, it is not. It is the *appearance* of intensity, based on the eye
>sensitivity of the standard observer, defined by tests many years ago by
>the International Committee on Illumination.
>Human eye response is sensitive in green and very weak indeed near the
>peaks of the photosynthesis action spectrum of most plants. As a result,
>better plant tubes oftern have far lower lumens per Watt than those that
>make for easier reading light, like "Cool White" fluorescents. Lumens
>and lux are terribly misleading when applied to plant growth.
>>and lumens is the measurement of light output.
>No. Of apparent visual light output.
>>and in bulbs is best defined by the efficiency, or lumens produced per watt.
>>which is saying very simply that not all watts are equal.
>True. Lower lumens per Watt are often better for plants. Compare
>"Daylight" to "Cool White" for example.
>>obviously, light is electricity converted to heat and light. the hotter
>>the bulb the less effcient. more heat less light. its a waste of energy
>>basically. your using twice the electricity to make more light at less
>>light per watt.
>>but sometimes this is needed, it's obviously easier to use one hotter
>>brighter light than alot more cooler more efficient bulbs.
>>so that seems to me to be very beneficial as to plants. maybe it's just me?
>This is muddled and confusing, at best. Different technology has
>different ways of converting power to light, but temperature isn't the
>whole story, by a long shot. Some discharge lamps waste lots of energy
>in the UV, which doesn't add anything to heat but is useless for plants,
>maybe even harmful.
>Lux and Lumens are superb for designing Dept. Store window displays, or
>lighting a work area. They are not as good as PAR or Einsteins (with a
>defined spectral range) for photosynthesis. Unfortunately the
>manufacturers give us the former, but rarely the latter.
>Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net - 760 872-3995
>"...watching Mayor Nagin and Governor Blanco handle the New Orleans/ Louisiana debacle is like watching Moe and Curly trying to work a Rubik’s cube."
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