Hey allen,
ik vond dit stukje text gequote op een ander wietforum (engelstalig) is daar ook als onbekende bron gequote.
ikzelf kan dit verhaal wel slikken, lijkt me toch wel enige logica in te schuilen.
Wat denken jullie ervan?
"20w CFL is rated at 1200 human lumens. The PGL (plant growth lumens) of a 20w CFL is 841. this means that the plant sees 70% of PGL in compaison to HUMAN lumens.
now lets take a look at a MH bulb. 50w MH is rated at 3000 HUMAN lumens. the PGL of a 50w MH is 1890. this means that the plant sees 63% of PGL in compairison to HUMAN lumens.
now we look at a HPS bulb. 35w HPS is rated at 2240 HUMAN lumens. the PGL of a 35w HPS is 1534. this means that the plant sees 68% of PGL in compairison to HUMAN lumens.
so for all you people that have a 400w HPS (myself included) which is rated at 55,000 lumens this means that the plant is only actually getting and USING 68% of those HUMAN rated lumens. so 68% of 55,000 lumens is 37,400 PGL. BUT lets also take into consideration what i mentioned above about LIGHT INTENSITY, that HPS light is 22 inches away from your plant. so our actual lumens is cut in half for every foot, so is the PGL, meaning that the 55,000 lumens HPS light is actually only 11,500 HUMAN lumens because we are almost two feet away. which also means that the PGL is cut down for every foot of distance meaning that the ACTUAL plant PGL is now only 9350.
what does this mean? it means that you thought you have 55,000 lumens in your your grow room, and YOU DO, looking at it with your HUMAN eyes. BUT, thru the plants eyes so to speak, its only seeing the 11,500. and you have done all your math based on HUMAN lumens.
so your 4x2 grow room has 8 sq ft. 55,000 lumens divided by 6 = 6875 HUMAN lumens per sq ft. BUT in all reality its 37,400 PGL divided by 8 = 4675 PGL sq ft.
but since your light almost two feet above your plant we have to cut that by half for every foot of distance, which gives us 1168 PGL per sq ft. so are we really acheiving our goal of 6000 lumens per square foot with our HPS, as measured in HUMAN lumens we are, BUT in PGL we are NOT!!
now back to our percentage of efficency of human lumens to PGL.
CFL = 70% MH = 63% HPS = 68%
"
is natuurlijk niet zo goed nieuws voor MH/HPS gebruikers als dit klopt, veel overbodig watt verbruik.
groeten,
cplifj
ik vond dit stukje text gequote op een ander wietforum (engelstalig) is daar ook als onbekende bron gequote.
ikzelf kan dit verhaal wel slikken, lijkt me toch wel enige logica in te schuilen.
Wat denken jullie ervan?
"20w CFL is rated at 1200 human lumens. The PGL (plant growth lumens) of a 20w CFL is 841. this means that the plant sees 70% of PGL in compaison to HUMAN lumens.
now lets take a look at a MH bulb. 50w MH is rated at 3000 HUMAN lumens. the PGL of a 50w MH is 1890. this means that the plant sees 63% of PGL in compairison to HUMAN lumens.
now we look at a HPS bulb. 35w HPS is rated at 2240 HUMAN lumens. the PGL of a 35w HPS is 1534. this means that the plant sees 68% of PGL in compairison to HUMAN lumens.
so for all you people that have a 400w HPS (myself included) which is rated at 55,000 lumens this means that the plant is only actually getting and USING 68% of those HUMAN rated lumens. so 68% of 55,000 lumens is 37,400 PGL. BUT lets also take into consideration what i mentioned above about LIGHT INTENSITY, that HPS light is 22 inches away from your plant. so our actual lumens is cut in half for every foot, so is the PGL, meaning that the 55,000 lumens HPS light is actually only 11,500 HUMAN lumens because we are almost two feet away. which also means that the PGL is cut down for every foot of distance meaning that the ACTUAL plant PGL is now only 9350.
what does this mean? it means that you thought you have 55,000 lumens in your your grow room, and YOU DO, looking at it with your HUMAN eyes. BUT, thru the plants eyes so to speak, its only seeing the 11,500. and you have done all your math based on HUMAN lumens.
so your 4x2 grow room has 8 sq ft. 55,000 lumens divided by 6 = 6875 HUMAN lumens per sq ft. BUT in all reality its 37,400 PGL divided by 8 = 4675 PGL sq ft.
but since your light almost two feet above your plant we have to cut that by half for every foot of distance, which gives us 1168 PGL per sq ft. so are we really acheiving our goal of 6000 lumens per square foot with our HPS, as measured in HUMAN lumens we are, BUT in PGL we are NOT!!
now back to our percentage of efficency of human lumens to PGL.
CFL = 70% MH = 63% HPS = 68%
"
is natuurlijk niet zo goed nieuws voor MH/HPS gebruikers als dit klopt, veel overbodig watt verbruik.
groeten,
cplifj
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