Re: [APD] Yellow HPS bulbs? No thanks.

["Daniel Larsson" <defdac at hotmail_com>]

David A. Younker wrote:

"The only globe / tube - based lamp I'm aware of that is more
efficient at
converting electrical energy into massive amounts of light output are
low
pressure sodiums. On _what_ are you basing your economic comparisons?"

On the fact that PUR-efficiency penalize yellow and that yellow light
doesn't drive the photosynthesis, and the fact that HPS:es have
any PUR-efficiency at all only is because what you state, they are
good at one single thing: Making lumens, yellow light that is:

>From Ivo Buskos article:

o numerically integrate the digitized spectrum over its entire
wavelength range, getting the total power S in relative units.

o knowing the bulb's total power consumption P in Watts, normalize the
digitized spectrum ordinate scale by multiplying the relative values
by P/S. This gives the bulb's spectrum in Watts/nm, assuming that the
conversion efficiency from electrical to electromagnetic energy is
100%.

o multiply the Watts/nm spectrum by the eye photopic curve (normalized
to unity peak). Integrate the result over the same wavelength range
used above, and multiply the resulting integral by 683 lumens/Watt.
This gives the theoretical maximum lumen output of the bulb.

o divide the bulb's rated lumen output by the theoretical one. This
gives the overall efficiency factor.


David A. Younker continues:
"NASA's energy constraints within the confines of a space vehicle are
the
dictating terms in their choices. Their choice of LEDs is based on
energy
consumption vs. desired goals, and they aren't as concerned with the
comparative startup or initialization costs as they are with the
effects on
their on - board battery system. Since I don't have Bill Gates's bank
account to use as a discretionary fund and don't ever intend to use
massive
and expensive batteries to run my tanks, this point is so moot that I
just
have to ask where you thought it figured into this debate."

LED:s are going cheaper, they don't require any electricity at all
(compared
to discharge lamps). As of now white LED:s are so-so because they are
made like flourescents with coats of phosphorus filtering the light
and thus
makes it less intense. Blue and red LED:s combined are hard to
calculate
PUR-efficiency for because they hardly put out any lumens at all
(which
is good).

HPS = much lumens for the buck, Blue+Red LED:s = no lumens at all but
serious growth compared to the electricity you put in.

Hope you see the difference.


David A. Younker continues:
"Hydroponic and greenhouse concerns such as Tropica are well aware of
the
running costs of various lamps and their systems - they use them in
numbers
that we can only fantasize about in our everyday life. Plus they have
well -
utilized, well - educated and highly - motivated research staffs that
make a
living at this sort of thing. All geared toward producing the maximum
amount
of vegetative growth to create a product that, after going through
several
layers of middlemen, still only costs me an average of US $3.50 a pot.
I
imagine that, to them, a difference in fractions of a penny in just
one
single lamp choice can amount to hundreds of dollars' worth of
electric bill
one way or another. Which ultimately affects their profitability."

This is interesting because Tropica resides in Denmark, next to Sweden
where I'm at. We have only a couple of hours of sunlight in the
winter,
and that is a time when Tropicas plant doesn't look especially good.

As I see it, all greenhouses that use HPS:ses waste energy, so it
would
be very nice for those rocket light scientist at Tropica stating on
what
grounds  they've choosen the light. Me thinks they will say something
like
 "most lumens for the buck". It's weird Tropica think the SunGlo-bulb
is good (very high lumens compared to other bulbs), when they actually
use other flourescents in their tissue-cultures. Very weird stuff
going
on there 8)


David A. Younker continues:
"Considering all of the factors involved in the phenomenon we call
"pearling", just what made you decide that the choice of lamps was the
single- most _deciding_ factor?..."

GroLux made my plants leggy and the light was poor (less lumens),
SunGlo made the tank look yellow (ugly), Biolux made it look green
although very truthful colors (high CRi) and Aquarelle/Aquastar
made my Glosso hug the substrate and all the red plants really
red, good pearling and good color, and also a color in the tank
I could live with. Most bang for the buck:
http://www.defblog.se/picture/1286.html

All this correlates will to the PUR-efficiency. Certainly vetter than
lumens-efficiency alone.



Best regards
Daniel Larsson



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