[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [APD] Green HPS bulbs? No thanks.
> From: "Daniel Larsson"
> Sent: Sun, 19 Mar 2006 13:10:53 +0100
> ...I didn't use my ears, but my eyes...
That part of my posting was meant to describe these discussions in
> ...This together with my eyes have convinced me long ago
> HPS:es are economically very bad...
> ...So true, but not if you want to really maximize growth
> to the energy you put in. I don't think NASA will use
> HPS:es when they will grow plants as fast as they can:
> ...This is not interesting for those that doesn't care when
> the electricity bill comes, they use HPS:ses or whatever
> crappy light they like the looks of and shoot as hard as
> they can. Brute force...
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?
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.
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.
> You also think the phototropic response is due to the 440 nm
> length which is not true:
What I stated was that phototropic *response* was maximized at around 440
nm. I never said absorption or utilization was maximized at 440 nm. Like a
feedback mechanism, various combinations of factors may increase the
pressure on the system to respond the farther away it gets from the optimal
The paper you proffered does indeed discuss the odd effects of red and far -
red light on phototropic response, but does nothing to either deny or
confirm the _degree_ of the response as affected by blue light - only
stating that the full effects of blue light and its receptors is not clearly
understood but should be studied, as it clearly factors in for phototropic
The effects of varying wavelengths of light, particularly in response
patterns, have been studied for at least seven decades' worth of published
papers, a good deal of which are available from the US Department of
Agriculture. The first one of these that I remember reading was printed in
1939, would probably take me some time to track down again, but it could be
done. The more recent research deals with the specific mechanisms that make
these responses possible to further our understanding, but does not
automatically throw out empirical data collected over many observations
based on simple Stimulus - Organism - Response reactions.
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?...
David A. Youngker
jaafaman at comcast_net
Aquatic-Plants mailing list
Aquatic-Plants at actwin_com