Date: Tue, 30 Sep 1997 18:15:13 +0000 From: drake@erols.com To: cp@opus.hpl.hp.com Message-Id: <aabcdefg3792$foo@default> Subject: -What you need to know about artificial lighting-
Dear Cp-list subscribers,
Here is some very useful information on artificially lighting
your plants that I have written from my information that I researched
recently during these discussions on the topic. To my knowledge this
material is fairly accurate. If anybody comes accross any conflicting
numbers or information please post it to the list. Thank you and
enjoy.
Terms:
Footcandle-The amount of light cast by one candle at a distance of one
foot. (a unit of light measurement)
Lumens-a unit of light measurement (definition irrevelant for
comparision purposes)
Coverage area is in ft. First is primary growing area, second is
secondary growing area. Imagine it as one square (secondary area)
drawn on the ground with one inside it (primary area).
Summer Sun, midday
------------------
Approx. 10,000-12,000 footcandles
Plants in window - can be 4,000-5,000 footcandles
Plants a few feet from window - can be 200 footcandles or less
--------------------------
ABSOLUTE MINIMUM Plant Light Requirements
--------------------------------
Footcandle Intensity - 1,000
Footcandle Qty. - 15,000
Footcandle Qty. = Footcandle Intensity * Photoperiodism
---------------------------
Flourescent Light (2 tubes)
---------------------------
-Cool White-
Light Penetration < 12"
Max. Suggested Plant Height Grown Under Flourescents - 8"
------------
Metal Halide
------------
-175W-
Lumens (Initial) - 14,000-15,000
Coverage - 2x2, 4x4
-250W-
Lumens (Initial) - 20,500-23,000
Coverage - 3x3, 5x5
-400W-
Lumens (Initial) - 34,000-40,000
Coverage - 5x5, 8x8
--------------------
High-Pressure Sodium
--------------------
-150W-
Lumens (Initial) - 16,000
Coverage - 2x2, 4x4
-250W-
Lumens (Initial) - 27,000
Coverage - 3x3, 5x5
-400W-
Lumens (Initial) - 50,000
Coverage - 5x5, 8x8
-400W- With SonAgro (Philips Brand) bulb with 30% more blue than
standard sodium bulbs - Lumens (Initial) - 53,000 Coverage - 5x5, 8x8
-----------------------
NOTES ON THE HID LIGHTS (Metal Halide and High-Pressure Sodium)
-----------------------
*1000 watt - approx. Coverage 8x8, 12x12
*ONLY BUY FULLY "UL" LISTED HID LAMPS!!!! for safety reasons!!!!
-------------------------
Summary - Drake's Opinion
-------------------------
Do what fits your needs. I'm probably going to buy a Metal Halide
lamp (fully UL listed, of course). And by the way, there are better
reflective materials than Mylar (which degrades and gets brittle over
time). Its been recommended to me that "Coilzac" is good reflective
material to use, but I do not have enough information to comment on
its usefullness or safety (heat buildup, electrical hazards, etc.)
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