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

> Date: Sat, 18 Mar 2006 16:16:08 +0100
> From: "Daniel Larsson"
> Subject: [APD] Green HPS bulbs? No thanks.
> To: <aquatic-plants at actwin_com>
> ....How much is it? Like 14-15% compared to the blue peak? Which
> lamp would you prefer to use to grow plants, an all 420 nm blue bulb
> or an all green 550 nm bulb?
> or like an HPS 600 nm bulb?
> HPS is yellow and green. Very yellow, and very green:
> http://www.brite-lite.com/Hydroponics/Charts/HPSSpec_Emis2.gif
> So at the end of the day, you could never ever convince me to use
> a green bulb to grow plants efficienctly 8)

I love these discussions - it's like listening to audiophiles in the '60s 
and '70s talking the specs on their stereos. So many people willing to pay 
extra hundreds of dollars to gain an added 0.001% response from their 
equipment when they left their _ears_ behind long ago...

Daniel - looking at the chart you reference, the area under both the blue 
AND green spectral curves _combined_ don't even equal the area represented 
by the red alone, much less the yellow. Just "eyeballing" the chart tells me 
that a good 70-75% of the illumination produced by the lamp lies above about 
570 nm or so, yet you persist in calling these "green" lamps because of the 
single spike that has captured your attention so thoroughly. Get out from 
behind that tree and look at the forest - even a single Redwood isn't as 
impressive as a whole expanse of them.

>> Date: Fri, 17 Mar 2006 17:47:55 -0800 (PST)
>> From: Thomas Barr
>> Subject: Re: [APD] Aquatic-Plants Digest, Vol 31, Issue 38
>> ...I've tried to tell people in the past this, few understood it.
>> "Blue light penatrates deep, makes plants all bushy etc, blah
>> blah." Nope, canopy formation in weeds competition really shows
>> the red/far red effect and how sensitive it is...

Good luck with that - I've been going against the red / blue  "conventional 
wisdom" since my first postings on the net, to little avail and even less 

from Dec 1997

and another thread from the same month:

all the way through some of my more recent "experiments" involving light 
spectra, intensity, CO2 and growth:



David A. Youngker
jaafaman at comcast_net

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