light penetration query

Right quick question guys and thanks for the info in advance. Ok so I'm gonna run 2 1000w hps in cool tubes above a 4x6' and have 96 sog plants. My question is, if the lights are cool enough to be hung say a foot n a half away, how would I calculate how far down would the light penetrate before it would be unable to make solid bud. I had a picture in my head of like 2' tall solid colas and maybe only 8" of stalk beneath. I know a light can only penetrate so far down but on everything I have read it has no mention of multiple lights. I really wanna know this so I know how far up the main stem I should remove everything. Thankyou dudes

not sure about 1000 watters but with my 600 the 3 foot plants have some nice hard nugs all the way down, its only about the bottom quarter that has the lighter fluffy bud, so my light penetrates around 2 and half foot.

look up the inverse square law for light

ROBSTERB said:

not sure about 1000 watters but with my 600 the 3 foot plants have some nice hard nugs all the way down, its only about the bottom quarter that has the lighter fluffy bud, so my light penetrates around 2 and half foot.

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What height do you have it from the plant rob? What kinda hood you using? Is it air cooled?What footprint is it set at?I wanna find a reflector/hood that will give me a 3x4' footprint at 1' from plant tops, any sujjestions? thanks a lot dude! Peace

My main goal is to concentrate on the optimal light distance from the plant to insure the best use and outcome at different wattage (400, 600, 1000). This will at least insusre you are getting the maximum penetration for your setup. For example 400 watts optimal distance would be 6-21 inches, 600 watts 8-29 and 100 watt 10-36. I'm not really sure how the cool tubes a effect the distances. I know this doesn't actually answer your question but oh well.

Swisher Sweet said:

My main goal is to concentrate on the optimal light distance from the plant to insure the best use and outcome at different wattage (400, 600, 1000). This will at least insusre you are getting the maximum penetration for your setup. For example 400 watts optimal distance would be 6-21 inches, 600 watts 8-29 and 100 watt 10-36. I'm not really sure how the cool tubes a effect the distances. I know this doesn't actually answer your question but oh well.

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No answer but good info my friend, ok so if I have my lamps between 10 and 36 inch away from canopy I can ensure the full length of my plant will receive good light. Now all I need to figure is what hood/reflector is gonna be best to cover the footprint I need, I wonder if those reflectors with a smaller footprint acctually deliver more light intensity to the area that is being lit up. I suppose it would because all the available light would be there but just concentrated to a 3x4 area as apposed to a 6x8 area? Does this make sense to u? Or might one be rambling ha! Thanks for the post dude peace

i use air cooled shades that measure 2 foot by 2 foot, there about 8 inches aboce my plants, my space is around 6 foot by 4 foot, ive also got a 400 next to the 600. def go with a cool shade, you can get them much closer so the light penetrates further down the plant, also mean more light hit the tops so the buds are bigger.

Originally Posted by uhavealighter?.

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here is a chart that may help. the glass in the hood will stop some of the light. and if the light is too close, it will bleach your plants.

God thanks guys that's some great info I can work by, really appreciate it. The first article is a little too complex for me to fully grasp whilst so stoned so I'm gona sleep on it and read it in the morning its been a long day lol thanks again dudes peace

jasman said:

No answer but good info my friend, ok so if I have my lamps between 10 and 36 inch away from canopy I can ensure the full length of my plant will receive good light. Now all I need to figure is what hood/reflector is gonna be best to cover the footprint I need, I wonder if those reflectors with a smaller footprint acctually deliver more light intensity to the area that is being lit up. I suppose it would because all the available light would be there but just concentrated to a 3x4 area as apposed to a 6x8 area? Does this make sense to u? Or might one be rambling ha! Thanks for the post dude peace

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I have always worked off the same chart smoke and coke posted thus the figures I gave you. The other post is interesting, technical but seems to be at odds with our determination on optimal foot candles. Now I am questioning which is accurate. The chart smoke and coke posted is at odds with the other info provided on optimal foot candles. I use two 400's and a 600 and use very simlple aluminum wings with great results. I keep my 400's at 6 inches and the 600 is 8 inches above the canopy. You can always improve your grow setup so reflectors, lights (cool tubes )etc. can always be options. I have great results so I stick with it. Your last question was "will moving your lights to the optimal level ensure your plants get thorough light the fulll length of plants". The answewr to this is not necessarily. The strain you have will affect this. For example I have 3 foot plants primarily because of space restrictions (thus not as much penetration is necessary vs. 6 foot plants). Also foliage can have an affect as some strains have significantly more than others. Taller plants are harder to get solid buds at the bottom. You could use some flourescents that you line the bottom of your grow space with to get more light to the bottom.

too far away and not enough light, too close and you create more shadows and less light (plus very uneven)


plus, if you get it too close and raise the temps too much At the buds, you will kill aroma and bit of the potency, (though it can be used somewhat for smell control lol)