Sunday, July 17, 2011

Christos Mpelkas: Gro−Lux Standard Phosphor Identification

>> I have always wondered what's the story behind the the GRO−LUX Standard
>> because, when I started growing plants in my apartment in the 70's,
>> that lamp often seemed to be the only available fluorescent plant light
>> in many department stores. There were plant lights from GE available
Re: Gro−Lux Standard Phosphor Identification

>> Do you know why Sylvania created what they did, (Gro-Lights) and why the other
>> manufacturers didn't bother to match the spectral output. That seems
>> to be the rule of thumb for about every other lamp type. Why did
>> Sylvania ALONE make so unique and truer match to plant needs?
>> I often visit and help people with lighting information in a gardening
>> forum, and this is a common question. Sylvania has pamphlets. but not
>> any deep technical history.
>> Ron Seadler

"Jeff Waymouth" <jfwaymouth3@xxxxxxxxxxx> wrote in message
> I'm afraid I can't answer that question. The only thing that I can say is
> that, for years and years, we had a photobiologist as a part of our staff.
> His name was Christos Mpelkas (Greek, Ionnis!) and knew more about all
> horticultural lighting applications than any person I have ever met.
> He retired about 10 or 15 years ago and died a few years ago.
> If you look deeply into the old engineering bulletins that GTE SYLVANIA put
> out, you will find his name associated with every single one.
> The only thing I can think of is that he knew this was the best
> formulation and insisted upon it.
> By the way, one thing I learned (long ago) from sitting inon one of his
> presentations is that the absolute best blend of light for sprouting and
> growing plants is NOT simply the GRO−LUX. It is a one for one mix of
> GRO_LUX and GRO−LUX Wide Spectrum. That provides the best red to blue and
> red to far red ratios for general plant illumination.
> A personal thought here, I have never understood how people can talk about
> light for plant growth in terms using foot candles for an intensity curve.
> Photosynthetically Active Radiation (PAR) is a much better measure, since
> foot candles are based on lumens which are based on the human eye's
> sensitivity curve, which is heavily green weighted (peaking at 555nm)
> which is a color are amost plants do not use at all (or how do we see
> their leaves as green?)
> Jeff Waymouth
> Zink wrote:
>> Jeff,


  1. I saw this page a year ago, but did not comment on it. I am Ron Seadler, aka Zink. I asked Jeff Waymouth these questions years ago in the newsgroup. I learned a lot about fluorescent phosphors from the guys in that group, mostly lighting experts and research lab folk. I found it interesting that Gro-Lux was the only lamp with a red phosphor that actually matched the chlorophyll absorption spectrum. Jeff Waymouth was kind enough to tell me about it.

    1. Ron..Sorry I didn't see your comments earlier. I hope you get this..I was fortunate to have become associated with Chris after his retirement, and was able to work with him during that time..I probably have as much information on Chris's work on my blog as any place, except UMass Amherst, if they ever put it on the shelf and make it public..thanks for writing..I will try and be more attentive to comments on my blog!!