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the d.o.c

lighting hint

171 posts in this topic

I place an oscillating fan pointed towards each of  my lamps(2 lamps 2 fans and this cools the lamp and shade considerably allowing me to get even lower to my plants without burn..............Orinoco :rofl:

I tried this but the radiant heat still frazzled the top leaves although the air temperature was OK. Lucky I noticed in time to move the light back up a bit

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I hang my 600W hps less than a foot away from my plants with only an oscillating fan for ventilation. But I have one of those heat shields under the bulb.

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what about enviros? does the same 'losing half intensity per 6inches" rule still apply? Ive got my plants about 6 inches away from my enviro. Only small plants mind, 3 inches tall.

Hiya Pinhead,for all types of lighting the inverse square law applies. Forget about 'losing half intensity per 6inches'.

The rule is,in laymans terms is that if you have a light emitting say 10,000 lumens at a distance of 2 feet and you double the distance to 4 feet,you will have 2,500 lumens of available light.

If you halve the distance to 1 foot,you will have 40,000 lumens of available light.

Simple,innit?

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Flours Grow Great Buds, Far worth of smoking, and eazy 400.00 a zip shit, my buddy harvested a QP off 1 flour plant, and it was some of the best smoke i've had, So fucking sticky eeky, and buds the size of 12oz soda can.

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:yinyang: im oretty sure halogens r not any good for growing as they lack the blue spectrum and half the red stectrum of a fluro

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Flours Grow Great Buds, Far worth of smoking, and eazy 400.00 a zip shit, my buddy harvested a QP off 1 flour plant, and it was some of the best smoke i've had, So fucking sticky eeky, and buds the size of 12oz soda can.

Where's me Babelfish? :oldtoker:

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Evening.

I've just upgraded from a 400W hps to a 600W hps,.with the 400 I kept the light 13" away and had no probs, Ive now got the 600 in there at 16" away. Does anyone think that's too close or about right?

Cheers guys, it all seems OK but I'm unsure :wassnnme:

Mr P :yinyang:

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I'm using a 400 too for vegging with a MH bulb,but will be flowering soon.

Mine's approx 12-13 " away from the top of the plants.

Is it a good idea to supplement the HPS with some cfl's i've got when flowering ?

They're those energy saving bulbs,and did a great job of starting them off.

If i do should i get them fairly close to get the most from them ?

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light intensity virtually doubles every 6 inches closer a HID is to the canopy of bud

light adheres to the "inverse square rule" ,i.e it diminishes to the square of the distance ,which can mean you may be losing a lot of your lights potential ,

always make sure your lights are at the right height to provide maximum lumens but not too close incase of heat and not to far away because it will be less efficient

here is a rough rule of thumb for lights

hang 1000w and 600w HID's 24-36 inches from canopy

hang 400w HID's 18-24 inches from canopy

and smaller HID's to 6-12 inches away

peace :headpain:

Good info for sure Doc, but I think you may have oversimplified it.

The inverse square law is just that, an inverse square. I think it might be better to explain what this means exactly, because it is not at all true that your light doubles for every 6 inches you get your plants closer to the light, as you are not expressing from where your starting point is.

Lets first give the definition: The energy 2 x as far as the source, is spread over 4 times the area. hence 1/4 the intensity.

Lumens for lights are measures at a certain distance, say 30 inches or so. For this example, we'll say that a 1000w ligth is producing 120,000 lumens at 30". Now, if you say put the point of measurent at 60", or 2x the distance, then your light would be split into 4, as it would be 2 times the width and length from the source point, or 1/4 the total lumens, or 30,000. This also applies the other way. At 15" the light would be 480,000 lumens.

This theory is often not accuratre however, as refletors cause light to be more concentrated over distance.

If you had a 100% reflective tube that a light shine down in, the light would come through the same as it went into, no matter how lkong it was. This only works thoeretically w/ 100% reflective material however, which to my knowledge does not exist.

BTW, lumens are an inacurate measurement of light for plants, and the PAR should be looked at when deciding the quality and light intensity for your grow.

I should also note that w/ proper cooling you can get a 1000w light w/in 12 to 18" of the top of a canopy. In fact, I would never pull a 1000 watter more that 2' from the tops of plants if you are using a 16ft2 area w/ indica dominant plants. This would be under an ideal nutrient program w/ and exerienced grower. REally though, a 1000 watter at 2', a 600watter w/9ft2 at 18", and a 400 6.25ft2 at 1' or less is ideal. Even those numbers are conservative, as like I said, you can get a 1kw at about 12" w/out light burn.

Anyways, the point was, your light will be 4x AS STRONG, EVERY TIME YOU CUT THE DISTANCE IN 1/2

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:)

Yes D.o.c., absolutely correct.

Also it helps to rotate the plants under the light, both on their own axis and around the growing area.

A downfall for us (mainly) NFT tank users unfortunately.

But, in a recent organic soil experiment I delighted in the ability to shift the plants around

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Heres one for you. How much cooler in a similar environment is a 600W than a 1000W lamp.

We're talking a 12m cubed jobby.

I'm downsizing and just settling in & wondered if a single 600W is ultimatley more productive than a single (staic)

1000W lamp, cause they cost a pretty penny to light up everyday.

Tightarse AM :doh:

Edited by Ambling_Madly

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Flours Grow Great Buds, Far worth of smoking, and eazy 400.00 a zip shit, my buddy harvested a QP off 1 flour plant, and it was some of the best smoke i've had, So fucking sticky eeky, and buds the size of 12oz soda can.

a quarter pound off of one flouro plant? :unsure: what was it 1200w?

:spliff::yahoo::rofl::yahoo::smug::rofl:

forma.

Edited by formabud

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a fisherman that likes to tell stories, maybe?

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Good info for sure Doc, but I think you may have oversimplified it.

The inverse square law is just that, an inverse square. I think it might be better to explain what this means exactly, because it is not at all true that your light doubles for every 6 inches you get your plants closer to the light, as you are not expressing from where your starting point is.

Lets first give the definition: The energy 2 x as far as the source, is spread over 4 times the area. hence 1/4 the intensity.

Lumens for lights are measures at a certain distance, say 30 inches or so. For this example, we'll say that a 1000w ligth is producing 120,000 lumens at 30". Now, if you say put the point of measurent at 60", or 2x the distance, then your light would be split into 4, as it would be 2 times the width and length from the source point, or 1/4 the total lumens, or 30,000. This also applies the other way. At 15" the light would be 480,000 lumens.

This theory is often not accuratre however, as refletors cause light to be more concentrated over distance.

If you had a 100% reflective tube that a light shine down in, the light would come through the same as it went into, no matter how lkong it was. This only works thoeretically w/ 100% reflective material however, which to my knowledge does not exist.

BTW, lumens are an inacurate measurement of light for plants, and the PAR should be looked at when deciding the quality and light intensity for your grow.

I should also note that w/ proper cooling you can get a 1000w light w/in 12 to 18" of the top of a canopy. In fact, I would never pull a 1000 watter more that 2' from the tops of plants if you are using a 16ft2 area w/ indica dominant plants. This would be under an ideal nutrient program w/ and exerienced grower. REally though, a 1000 watter at 2', a 600watter w/9ft2 at 18", and a 400 6.25ft2 at 1' or less is ideal. Even those numbers are conservative, as like I said, you can get a 1kw at about 12" w/out light burn.

Anyways, the point was, your light will be 4x AS STRONG, EVERY TIME YOU CUT THE DISTANCE IN 1/2

Yes I said what you've stated but in about 3 sentences and I did'nt say the intensity doubles every 6 inches that was someone else old bean. :yinyang:

Edit:Sorry chum,my mistake,you were referring to another doc in another post.It is late and I'm tired!

Edited by dr rockster

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Flours Grow Great Buds, Far worth of smoking, and eazy 400.00 a zip shit, my buddy harvested a QP off 1 flour plant, and it was some of the best smoke i've had, So fucking sticky eeky, and buds the size of 12oz soda can.

:yinyang::starwars: glad the kids r back at school now

Edited by mr_green01

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