# to much light?



## blondlebanese (Oct 21, 2014)

I was able to make  some temporary walls out of painted cardboard and shrink my grow space from 15 sq ft down to 8 sq ft.  by placing my floro lights against each other, side by side. I was able to fit all 80000 lums in the 8 sq ft space.  if my math is right and I understand the formulas, that would give me 10000 lums per sq ft.  plants are only average 8 to 10 inches tall lots of new growth.  the branches are closely spaced. in about 10 days I plant them in larger pots the temp walls come down and they get reduced to 5300 lums per sq ft. for the remainder of the veg cycle.  anybody forsee problems with that?


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## stonedagain714 (Oct 21, 2014)

ive never grown with floros,my thoughts would be will floros give enough penetration for a good grow.my plants usualy end up about 3 to 3 and a half feet. as far as lums per square foot go you are in good shape.


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## The Hemp Goddess (Oct 21, 2014)

There is a point that plants are not able to utilize any more light.  However, if the light is not bleaching the plants and you can control the heat, it is not too much light...but it may be more than you need.  The big think is not to crowd your plants.  Is there room around each plant or are they all squished up together?  If you get them too crowded, you will not get the light penetration and no matter how much light you have, they will stretch.


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## umbra (Oct 21, 2014)

I am sorry but there is no way fluorescents are putting out 80,000 lumens. And no way you are at 10,000 lumens. Even if you lined the space with floro's, no way near those numbers. Maybe 1,000 lumens...maybe!


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## The Hemp Goddess (Oct 22, 2014)

LOL--umbra, I didn't even think of that.  I think he is running T5s--so, 5000 lumens per 4' 4W tube.  Yeah, there is no way to even get that many tubes in a 2 x 4' space.


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## blondlebanese (Oct 22, 2014)

the temporary space I created is2' x 4.25'.  side by side the t5 hop fixtures take up less than 20".  that's 8 fixtures, 16 bulbs.  I don't understand why only 1000 lumens?  I thought 54w hop give off 5000 lumens x 16 = 80000 divided by 8.5 = 9412 lumens.  if I'm wrong then please correct me.


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## Hushpuppy (Oct 22, 2014)

If you are using 8 of the 2bulb ffixtures, then you can fit them in there packed tight and achieve that. But are they more than 10" away from the plants? Floro light loses energy quickly so you have to keep the lights close. If you are able to achieve that, then I wouldn't keep the space that tight as you will probably have heat buildup pretty quick. For vegging, you only need to achieve 4500 lum per sqft to have excellent results. 10K is a waste of energy in my opinion.


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## blondlebanese (Oct 23, 2014)

from what I gathered I understood that 3000 lumens are what is needed to veg.    you say 4500 still isn't that the minimum.  so I thought more than minimum is better.  am I wrong?  won't the extra light keep the branches close and not let stretch happen?  also doesn't the extra light help to penetrate?  I read that light from a single source is better than light that is spread out.  it seems to me having the lights clumped together helps  penetration.    maybe I don't understand what is meant by penetration or how the light penetrates.  does it mean the light pierces the leaves or does it mean the light penetrates by reflecting off the walls to reach the bottom of the leaves.  if the latter was the case then light spread out over the canopy would be more beneficial, it seems to me.  or if light energy is heat maybe its heat that the plant needs.  comeing from one source would be more beneficial in that case.   signed  confused


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## Hushpuppy (Oct 24, 2014)

This may take a minute 

3000 lums ffor veg is the minimum, but I have found ffor me personally that I get very good response from my vegging plants when I get about 4500 lumens. Anymore than that doesn't seem to increase the benefit so I just stay at that level for veg and I try to get 6500 lums for flower. Anymore that that on either of them, I believe is a waste of watts.

Keeping the lights close together is good as it allows you to concentrate the available light energy ffrom those bulbs into a smaller grow area. That is good because the bigger the grow area for a given set of lights, the lower the amount of lumens per sqft. This is the concentration of energy or "saturation". Some would say this amounts to the intensity as well. But if you are only needing to achieve 4500 lum per sqft and your lighting for that space is giving you 10,000 then you can either lesson the light to the 4500 or you can open up the space until the rate of dispersion lowers the Lum per sqft to the 4500. Opening the space up some will allow more penetration on the plants while allowing better air circulation for the plants, and it will lower the heat that is concentrated in the grow space.

Light from a single source versus light that is spread out, is a moot comparison. because the key for this is lumens per sqft and the amount of penetration that the lights produce. You can have 1 600w light that gives the right amount of lumens per square foot for a given space like a 4'x4' tent, and you will have no problems. Or you can set up a scrog and have 2 400w lights setting side by side but being a little closer to the plants so that they get the maximum output of the lower wattage lights, and the scrog keeps the canopy at one level so penetration is no an issue. With the 2 400w lights, you will achieve the same results or maybe a little better depending on your grow methods as you would do with the single 600w light.

Now penetration is the distance the photons of light will travel without loosing more energy than the plant needs for photosynthesis. As light travels, it loses some of its initial energy given to the photons at the light source. This is because the photons meet air molecules and anything suspended on them as they fly out from the light source, and that creates resistance which drags away some of the energy. Also the photons disperse into an open space and the more space they have, the more they spread out, which gives them more time to lose energy.
Plants need a certain amount of energy from each photon that hits their leaves or they cant do the chemical processes that they need to do. Iff those protons travel too ffar and lose enough energy to drop below the threshold of usable energy by the leaf, then that energy is wasted as heat on the surface of the plant. The distance that photon can travel before its energy level drops below the usable threshold is its level of penetration.

When ever light has to travel to a wall and then bounce back to the plant, it is losing that much more of its energy before making contact with the leaves.

Now with floros, you don't have as much penetrating energy as with the HID lights, but you have a lot of it being evenly dispersed. That makes the floro ffixtures good for small vegging plants because you have many plants that you want to keep close enough to the light source to get good even lighting energy to all parts of the plants. The T5s are cool enough and even dispersing enough that you can place them closer to the plants without burning the plants with intensity or heat. So you can spread out your lights a little and open up the space to allow for better air flow which is important, but still get all of the lumens that the smaller plants need.

When vegging or flowering bigger plants, I prefer 2 light sources to one as that will give you deeper penetration off the HID light but also give you light hitting the plants from 2 angles which reduces shadowing on lower growth. I hope all of my "lighting 101" ramblings makes sense to you rather than confuse you more.


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## blondlebanese (Oct 25, 2014)

I understand.  great info.  thank you.


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## Dman1234 (Oct 25, 2014)

I dont know if this has been said but 20 inch ho T5's (aquarium lights) are usually 18 Watts, the 4 footers are the 54 watts


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## blondlebanese (Oct 26, 2014)

t5 aquarium lights  would they work for rooting clones?


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## Hushpuppy (Oct 26, 2014)

They would work but they are a little expensive. If you set up a specific clone rooting area and you need proper lighting, you can either get a couple dual bulb 2' T5 ffixtures from Home depot/Lowes type store. Even Target or Walmart may have these. They don't have to be the high power lights as you don't need a lot of light for rooting cuttings. You would use just the one fixture over them while they are rooting then, when the clones get rooted and you want to leave them a little longer in that space before moving to a veg space, then you can turn on the second light fixture to give them enough veg light until they can be moved.

I used to have a cabinet that I built specifically for cloning and I kept 2- 2bulb 4'T5 lights in it. When my cuttings were rooting, I only used the one bulb in one fixture until the plants were fully rooted and had begun to grow again. Then I turned on the second bulb for a few days, then turned on the second fixture so that they would have enough vegging light until they were bigger and could be moved to my veg cabinet.


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