# Lighting - The Missing Pieces



## urville (Sep 20, 2004)

ok... not to beat a dead horse... and i saw the post below it's very fat and bloated.. so Die Horse Die!
seriously though this is the truth about to my recollection

kelvin makes no difference except to our pleasure of viewing and is rarely very accurate

lux is a unit of measurment of the intensity of a light source reaching any surface. in fact lux is the better deinfed as the measurement of lumens per square meter. period. i dont remember any of that green/yellow stuff.

and lumens is the measurement of light output.
and in bulbs is best defined by the efficiency, or lumens produced per watt.
which is saying very simply that not all watts are equal.
obviously, light is electricity converted to heat and light. the hotter the bulb the less effcient. more heat less light. its a waste of energy basically. your using twice the electricity to make more light at less light per watt.
but sometimes this is needed, it's obviously easier to use one hotter brighter light than alot more cooler more efficient bulbs. but i think alot of people who dont need that level of light are using them and paying huge bills for no reason.

more than anything except intensity, light first has to be in the right spectrum. period. or your wasting your time.
this is the action spectrum for chlorophyll Synthesis








if you arent hitting these areas your wasting light, specifically 425-475 and 650 to 680 nm's. and you want to hit these in the same intensities. theres no point in overshooting this curve. in fact with too much red your plants will be spindly, and too much blue shorter plants, and if you have an algae problem an excess of blue light is a great way to compound this problem. it doesnt hurt to come as close to the curve as possible. Funny enough most of those grow lights everyone seems to shun hit exactly these areas.

i never got people not using halogens, they are practically the same thing as a metal halide. They use the same tungsten filaments and the same spectrum. if its cost though, then i believe mercury vapors are the cheapest high light version, and then i get it. but not if they are using metal halides, halogens are much cheaper as far as equipment cost.

thats how i understand it from what i learned..


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## urville (Sep 20, 2004)

oh i forgot, fluorescents are mercury vapor lights, just like halogens are metal halides and vice versa. the difference is the scale, that fluro's have a coating to create different spectrums, and the format by which they are instituted.


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## shalu (Oct 1, 2004)

hm, halogens are about as inefficient as incandescent(about 17 lumens per watt), which is FAR less efficient than metal halide.


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## urville (Sep 20, 2004)

haha, that would explain it then!


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## shalu (Oct 1, 2004)

that's why my halogen floor lamp uses 500watts, ouch! I haven't turned it on for a long time, LOL.


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