Compound Lighting?

BSIv2.0

BSIv2.0

Well-Known Member
If I have 2 HIDS of the same wattage (400w) and use both for flowering....Would the light the plants recieve be equal to 800W of HID light?

Or will the plants get only 400watts of light....just more intense?

If they are positioned in pretty much the same place.

Area is 2'wx9'lx7'h
 
potpimp

potpimp

Sector 5 Moderator
Why would you want to put them in the same place? Put all your plants as close as you can beneath the lights (don't burn them like I did) and if you don't have to use but one, don't use but one. 800w is gonna run your electric bill up pretty good; better cut back where you can.
 
BSIv2.0

BSIv2.0

Well-Known Member
Thanks for NOT answering the question.

I've Been running the lights for 3+ months in seperate areas (veg/flower). So Elec isnt an issue.

My question was about intensity of the light.
 
T

thekeefmaster

Active Member
a watt is an electrical term not something that has to do with the light output if you put the lights next to each other, the plants would recieve double the amount of LUMENS(the measurement of light output) but its prob not as efficient as just one like the other guy was saying you most likely wouldnt be able to keep them at the same height why not try it out? your plants will let you know if its a good thing or not
 
Gygax1974

Gygax1974

Just some idiot
Especially in a small area like that you will have some overlap, where you have overlap you have more intense light. So yep more light/lumens, wonder what you're going to be getting lumen-wise per square foot? Not sure what your lumens are but it's about 45 watts a square foot...so doesn't sound like overkill, what about the heat? What's your heat like?

I am no lighting expert but I would think that it might be beneficial if you had a well ventilated area, your plants would definitely like you bunches for it.
 
BSIv2.0

BSIv2.0

Well-Known Member
The heat is fine considering....When both lights are on...Temps get up to 85 or so. With one light on it stays about 80-82. Thats with no real venting. Just my open doors and ac.....during the summer.

Today the temp finally dropped here. Its in the low 70's. And my ac just went out last night (talk about lucky). They will fix it today. But with no ac running and both lights on with these cooler temps....My high is 80 w/ both on. So I should be fine for the coming months as far as temps. Hopefully.

And yeah...The overlapping of the lights was what I was wondering about.

Not sure....a 400w covers roughly 3x3 sq ft. @ 50w per sq. ft. Im sure using two wont double that wpsf. But is should give it a boost.

Im sure its not like I having a 800w light (if they existed).

When its time for 12/12 I'll see what happens.
 
Gygax1974

Gygax1974

Just some idiot
Yeah I'm curious too, I also think it's not equivalent to an 800. I've seen a bunch of lighting discussions debating similar things like is a 400 and a 600 equal to a 1000 watt. Beyond me for the time being, I'm not that into learning about light really. So if it was equal to an 800 and you were growing in a 3x3 area it would be over 80 watts a sq. foot....eekkkk. I wanna see how you do, I was thinking about adding two of my lights. One thing for sure is you could have a bigger area to grow in. Wonder which is better for you? More intense light or a bigger area with more plants?
 
closet.cult

closet.cult

New Member
BSIv2.0 said:
If I have 2 HIDS of the same wattage (400w) and use both for flowering....Would the light the plants recieve be equal to 800W of HID light?

Or will the plants get only 400watts of light....just more intense?

If they are positioned in pretty much the same place.

Area is 2'wx9'lx7'h
Click to expand...
sorry to disagree. but two 400w lights do not equal the luminosity of one 800w lamp. what is does is spread 400w more evenly over your grow space so the plants that would normally be on the outside edges receiving less lumens will respond to that extra light.

so, you ARE increasing lumens to distant parts of your garden. or you could say, with two 400w lamps, you are really only increasing the size of your garden.

while it does look 'brighter' to the human eyes, luminosity has not been increased. the only way to increase luminosity, technically, is to increase your lamp wattage.
 
Gygax1974

Gygax1974

Just some idiot
closet.cult said:
sorry to disagree. but two 400w lights do not equal the luminosity of one 800w lamp. what is does is spread 400w more evenly over your grow space so the plants that would normally be on the outside edges receiving less lumens will respond to that extra light.

so, you ARE increasing lumens to distant parts of your garden. or you could say, with two 400w lamps, you are really only increasing the size of your garden.

while it does look 'brighter' to the human eyes, luminosity has not been increased. the only way to increase luminosity, technically, is to increase your lamp wattage.
Click to expand...
Even in the area where there is overlap? Just curious....I hate reading up on lighting it bores me...lol.
 
closet.cult

closet.cult

New Member
Gygax1974 said:
Even in the area where there is overlap? Just curious....I hate reading up on lighting it bores me...lol.
Click to expand...
yes, even where they overlap, it is just two sources of 400w. luminosity has not increased.

but don't get me wrong, the plants have more light in the room. 400w is spread out further and it reaches more spots without a light mover. but the total lumens don't increase.
 
Gygax1974

Gygax1974

Just some idiot
closet.cult said:
yes, even where they overlap, it is just two sources of 400w. luminosity has not increased.

but don't get me wrong, the plants have more light in the room. 400w is spread out further and it reaches more spots without a light mover. but the total lumens don't increase.
Click to expand...
OK, just in my head it doesn't add up...lol. I am not a good light thinker apparently. Good thread though, I need to learn this stuff but I hate it...I always skip over it when reading my grow books...lol.
 
aeiou

aeiou

Active Member
closet.cult said:
yes, even where they overlap, it is just two sources of 400w. luminosity has not increased.

but don't get me wrong, the plants have more light in the room. 400w is spread out further and it reaches more spots without a light mover. but the total lumens don't increase.
Click to expand...
careful... you say luminosity hasnt increased?...in relation to what exactly? you are correct in saying that you cannot "technically" increase luminosity unless you increase wattage, however, in the places where the lights overlap, there are indeed more lumens of light hitting that overlap area than there would be if only one light were hitting that area. light at its most "elemental" level is just photons and in the case where the lighting overlaps, there are more photons hitting therefore increasing intensity. thats why it looks brighter... because it is.
in conclusion you are correct in saying (output)luminosity of the lights doesnt increase but the amount of light hitting the particular overlap area does increase. its science.
 
aeiou

aeiou

Active Member
aeiou said:
careful... you say luminosity hasnt increased?...in relation to what exactly? you are correct in saying that you cannot "technically" increase luminosity unless you increase wattage, however, in the places where the lights overlap, there are indeed more lumens of light hitting that overlap area than there would be if only one light were hitting that area. light at its most "elemental" level is just photons and in the case where the lighting overlaps, there are more photons hitting therefore increasing intensity. thats why it looks brighter... because it is.
in conclusion you are correct in saying (output)luminosity of the lights doesnt increase but the amount of light hitting the particular overlap area does increase. its science.
Click to expand...
i have to correct myself... light is not "just" photons because light is dual-natured. it acts as both a particle and a wave. but in this case we can simply consider its particle tendencies. its science.
 
T

T.H.Cammo

Well-Known Member
Don't be too dependant on thinking in terms of "lumens", that's just a term that most people find easy to understand. Plants don't really operate on "lumens", they operate on "micro-einstiens" (m-e). A micro-einstien is the measurement of how many light photons actually hit the plants' light receptors. Two sprinklers will put out twice as many drops of water than a single sprinkler (even if they are placed side-by-side); therefore two equal lights should put out twice as many photons as a single light.
BTW, I would suggest seperating your lights to get optimum coverage. With a 2'x9' grow area. I would space the lights 27" from each end, with a 54" gap in the middle. Just my $.02 worth!
 
nongreenthumb

nongreenthumb

Well-Known Member
If this was the case everyone would be running 2 600w's in a reflector as opposed to a 1k.

The light may appear to be brighter, because it is hitting more surface area from more angles and is reflecting into your eye to make the surface appear brighter but where the overlap is I don't believe that the light actually increases,
 
aeiou

aeiou

Active Member
nongreenthumb said:
If this was the case everyone would be running 2 600w's in a reflector as opposed to a 1k.

The light may appear to be brighter, because it is hitting more surface area from more angles and is reflecting into your eye to make the surface appear brighter but where the overlap is I don't believe that the light actually increases,
Click to expand...
that makes absolutely no sense.
 
aeiou

aeiou

Active Member
T.H.Cammo said:
Don't be too dependant on thinking in terms of "lumens", that's just a term that most people find easy to understand. Plants don't really operate on "lumens", they operate on "micro-einstiens" (m-e). A micro-einstien is the measurement of how many light photons actually hit the plants' light receptors. Two sprinklers will put out twice as many drops of water than a single sprinkler (even if they are placed side-by-side); therefore two equal lights should put out twice as many photons as a single light.
BTW, I would suggest seperating your lights to get optimum coverage. With a 2'x9' grow area. I would space the lights 27" from each end, with a 54" gap in the middle. Just my $.02 worth!
Click to expand...
two equal lights will put out twice as many photons as a single light *of the same wattage/size.* If he were to put in the 800 watt lamp versus the (2) 400 watt lamps, then this would not be the case.
 
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