A 400 W lamp or 40 W lamp says nothing about how much light it puts out of any kind. Most
lamps use this wattage to drive themselves. On the avg about 75% of the wattage is for
driving it the other 2%% will be actual light output Some of the more hi-tech stuff drives
more light output, as it use less wattage to drive it.A simple way to look at it is to
look at the wattage and the lumen output. A 100 W bulb that has an output of 10,000 lumens
( say a MH) has an EFFICACY of 100 ( 10,000 / 100). A std incandescent. only has an
output of about 10 lumens / W, so you would need a 1,000 W lamp to be equal 100W MH in
lumen output.

But all this is based on the human eye, which is most sensitive to about 540 nm or green
light. You do not see red or blue light well, so when dealing wit actual light output one
needs to look a "Einstein's", a true light measurement of all light. Or a SED( Spectral
Energy Distribution ) Curve ( you know that nice colored rainbow plot you see on some
light bulbs)

Watts / gal is a MEANINGLESS value !! Why ? How deep is the tank, how wide is the tank,
what kind of bulb ( NO, VHO, CF, MH, MV, as they have a different "Point Source") and K
value, what is in the tank, etc..


--
Boomer

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Former US Army Bomb Technician (EOD)
Member; IABTI, NATEODA, WEODF, ISEE & IPS

If You See Me Running You Better Catch-Up


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