We really need a better 3D light saturation standard

[magiccannabus]

I've been designing a cabinet for a rather unconventional growing style. Basically I have 512W of fluorescent T8 shop lights hanging vertically around a 2.1 square foot growing space. The actual bulb surface area of the entire grow is about 16.75 square feet, making it roughly 965 times the surface area of an average HID arc tube. At roughly 45,000 lumens rated, I would hypothetically be working with 45,000 lumens right? Well, it's trickier than that because lumens are rated at 1 foot from the source. Thing is, there's not a single spot of plant in my cabinet that will be more than 8 inches from any source of light.

Since it's over 900 times less intense, plants can be placed against the tubes with no problems if they just happen to grow against them sometimes. It helps to think of my grow sort of like SOG or Scrog where you have lots of little bud colas. Only I'm planning to grow these out sideways in all directions from the central stem. I'm going to grow the main stalk vertical and then let it train itself toward the light. I may tie it down too so the bud colas end up facing tip first toward the tubes. Think corn cobs up a stalk if you want to get some sort of mental image. I want a solid plant top to bottom.

So this got me wondering. The normal thresholds for watts per square foot, rules for intensity, lumens, etc. all don't work well for my cabinet. Since I'm using my vertical space more than anything, but essentially creating a sideways sea of green all around the stalk. An HID is a point source and so the intensity of the lamp creates a lot of zones of lower intensity depending on how the lamp is used and if it's the only lamp or not. You get the beam of light with it basically. With my setup, the whole space is evenly flooded with light from all sides. Not just that, everything is less than one foot so the lumen rules have to be adjusted. At six inches I think the lights are supposed to be 4 times as intense, at 2 feet 4 times less intense. I'm not sure how to calculate it all. I'd love to be able to draw a saturation diagram of my cabinet using solid science.

How do I calculate the radiant light in here? Will I need to get some sort of expensive light meter to solve this myself or is there some sort of existing calculation rule for calculating light saturation per cubic foot?

 

[FreezerBoy]

Ever seen a Phototron?

 

[magiccannabus]

Yeah man the Phototron was one of my inspirations. As were many old pics I had from Overgrow of makeshift uses of shop lights. The main problem with the Phototron is that it has clear panels letting a lot of light out. It's definitely not a concept I came up with. I'm just using it a bit differently than I have ever seen anyone use it. This is fun in a way, but also intimidating because it's a lot of uncharted area...........

 

[knna]

Lm is an unit that measures absolute emission of light of a light source. It not vay with distance, as it refers to the light source, not the surface/volume being lit. Your bulbs emits 45000lm. Warm white fluos emits 14-15 micromols of photons (uE) for each Klm, so its about 650 uE, a very similar amount that a 400w HPS (emiting 58000lm).

What you are interested to know is the light density you achieve with your way of using them. Units used to measure this are lux (lm/sq meter) or uE/m2.

Due the uneven distribution that HIDs produces, often when you gives the light from all the directions using large lighting areas you may use slighty lower light densities. About 25 uE per cubic foot is enough light to get good buds.

The only way to calculate what you want to know is using sofware for light design. You can use Dialux, as its offered on some light's manufactures websites (try in Phillips) by free. Its a CAD, you need to build the space first (dimensions, colors, etc) and then place the tubes. It calculates any photometric value in the space.

A good trick to know well how light is being distributed is placing some measuring planes on the space, usually some horizontal ones (at different heights) and at less one vertical on the center of the cab. The program plots light densities along each of the planes using different ways (gray scales, isolines, etc).

 

[magiccannabus]

Oh sweet tool man, this may be exactly what I need! I will report back on it. I'm using mostly Philips tubes too, so this software should hopefully have prefab T-8s in it.

 

[magiccannabus]

Here's a pic of my space so you can see why it's so confusing....

 

[knna]

Seeing the light setup is almost simetrical, you can estimate very well light density using averaged figures. As light is being emited from floor to roof from all directions, and floros are low intensity sources, averaged figures will provide a good orientation: divide lm by cb ft. If its about 2Klm/cb ft or higher, its perfect.

Floros dont give excess intensity still being very close to plants, so there is almost impossible some point on the growing volume gets iluminance over 45Klm/m2 (~650 uE/m2) and most of the space is going to range between 25-35 Klm/m2, levels that plants use more efficiently than higher ones and that allow to grow fat enough buds. Of course, this is a guess estimate, as i dont know the size of the cab, but im used to this guessing at work. If the cab isnt much large of what im imaging, those figures are give or take correct.

 

[magiccannabus]

Thank you for your reply. That's very useful info to think about. I definitely don't think they're going to need all 8 of these flipped on at the same time until they're getting pretty big. I'm still trying to determine what the stretch will be. My only known strains right now are Colombian Trainwreck, Purple Haze, and I am germinating some Trainwreck x Sour Diesel. I know a more solid indica might train better for this job, but I think these strains are workable. I'm not sure on the names of 3 other strains I have though. The guy I got the clones from has not clarified that yet unfortunately. I am hoping these strains will be heavy and light-hungry enough. My math sorta seems to come up with a rough 11,200 lumens per cubic foot, but hopefully that's within the tolerance of the plant. I'm not sure what the maximum absorption per cubic foot is for the plant chlorophyll. Should be fun anyway.

 

[Capn]

Can't wait to see some plants in that cab man. I have a feeling they're going to like it.

 

[spangles]

This is very cool, seeing the cab and especially hearing from knna...very sexy geek stuff I especially like learning about.

For that space I guess 2 plants would max you out. Also it may bee a good idea to LST radically so that the top is tied to the base to form a "hoop" so that the auxins force flowering downstream all along the stalk so you could get the corncobs you mention.
Looks like an elegant setup, I look forward to a grow journal. Best luck

 

[magiccannabus]

Thanks for the feedback folks!

Spangles, I'm going to try to keep the plants as straight as possible at first when in veg. Toward the very end of veg I think I may lay them on their sides and rotate them to encourage side growth. I definitely will be placing a baggie over the very top and then spraying down the sides with kinetin(synthetic auxin) spray to promote branching.

I've studied the Phototron a lot, but I've had trouble finding out how the plants will train relative to the light and if the stretch is still vertical or horizontal. I mean, what if I veg these only half the height of the cab and find out they don't stretch upward at all? I really want to find more info on that. Side-lighting in general is not as well-documented as I would like, and most of the lighting info is geared toward top-down HID lighting. It's all very frustrating.

Without even calculating the overlapping fields of light, each square foot of fixture surface area has about 32W, or about 3100 lumens(at 1 foot). This is my complaint about the lighting standards. I've tried to use Dialux to do this, but I haven't quite figured out how to make a fixture in it. They have the fixtures divided up by brand and not by type which is REALLY annoying. I want just a generic shop light entity so I can really model this cabinet properly.

 

[purpledomgoddes]

for further interest in supplying light source(s) to vegetables, do search on par (photosynthethically active radiation). the actual spectrum(s)[wavelengths] of the light source(s) are just as interesting. roughly 550-750 nanometer spectrums (blue to red) influence chrlorophyl a & b.
uvb+floro+party light bulbs together w/ any other source give fuller representation of suns radiant energy.
just for interesting info. no attempt to assert this/that better.

 

[magiccannabus]

I thought PAR started somewhere around 400nm on the blue end. I know pot is ideal at 420-460nm for blue and 660-690nm for red. These lights definitely emit a lot of useless output in the 460-660nm range, but I've been considering getting some Philips Plant and Aquarium tubes.

 

[purpledomgoddes]

the relative photosynthethic response ranges, apparently (no body of work can definitely say for all plants), ranges from ~350-850nm.

blue light:350-500nm
chlorophyll a catalyst
auxin
cell activity
split of water atom
influence on movement of plant

green/yellow500-650nm
limited to no response. plants reflect green light and so seem green to human eye. why green lights can be used @ dark w/out interrupting dark for plants. party lights are effective cheap option.

red light600-700
sugar production catalyst
chlorophyl b production catalyst/engine
seed germ signal
chloroplast adjustments to light
siganl light/dark times
chromosome catalyst/engine
soil composting enzyme catalyst

far red 700-780nm
signal seed dormancy
signals internode stretch

uvb already documented as catalyst for fruit end quality. ~ 300-400nm for uv.

 

[knna]

I've studied the Phototron a lot, but I've had trouble finding out how the plants will train relative to the light and if the stretch is still vertical or horizontal. I mean, what if I veg these only half the height of the cab and find out they don't stretch upward at all? I really want to find more info on that. Side-lighting in general is not as well-documented as I would like, and most of the lighting info is geared toward top-down HID lighting. It's all very frustrating.

Without even calculating the overlapping fields of light, each square foot of fixture surface area has about 32W, or about 3100 lumens(at 1 foot). This is my complaint about the lighting standards. I've tried to use Dialux to do this, but I haven't quite figured out how to make a fixture in it. They have the fixtures divided up by brand and not by type which is REALLY annoying. I want just a generic shop light entity so I can really model this cabinet properly.

Yep, plants with mostly side lighting tend to branch more and grow less up. During vegging, plants needs way less light, so it makes sense just use an overheat shoplight during veg, or at least, during early veg (3-4 first weeks).

Most growing setups have its own veg cab, so you put the plants in the flower chamber once they are large enough to use the light. Most stretch happen on the first 2-3 weeks after flipping to flowering photoperiod, and for the rest of the flowering time plants will use all the light if the size when starting bloom is right (it depends on the strain more than to lighting, although it affects, obviously).

If you work with clones, and you dont have a separate veg chamber, or you dont want to give long veg periods, you can always may put a self on the middle of the cab and grow two rows of plants (or just 2 plants, one over the another; all depends of the strain and the size of plants you use).

Dialux is a free program done for lighting manufacturers to help designing with their own luminaries. Only expensive sofware allows to enter your own luminaries.

But you can simulate most light fixtures with the catalog of main lamp's manufacturers. You need to select luminaries very close in size to what are you using (not difficult at all with shoplights, all have very similar dimensions) and that gives a light distribution similar to what are you using.

This often requires some previous lighting background, but in the case of shoplights, again its not difficult. Choose any open shoplight with a wide distribution pattern, wich is like emits most of them. Once choosed and placed the luminarie, you can adjust the lm output, so you only need a similar luminarie. Shoplights have a caracteristic light distribution pattern, wide and simetrical, and almost any one on the catalog is going to work decently in the simulation. Choose the simplest one, as its what you have in there.

On the other hand, Dialux is a great tool to design the lighting of a grow cab. But once you already have built it, probably a light meter is going to give you the best info. Actual, not calculated info. You dont need a very accurate one, any cheap lux meter is fine, as far as it have a wide range of lux. Many only reach up to 50000lux (5000fc)~, and its often too short for our application. One with at least 10000fc is required for this task (although once you buy one over 50Klux, mostly its 200Klux). There are some of them online below 30$.

 

[knna]

green/yellow500-650nm
limited to no response. plants reflect green light and so seem green to human eye. why green lights can be used @ dark w/out interrupting dark for plants. party lights are effective cheap option.

Although many of the info of the quoted post is simplified, and some questionable, i want to put emphasis on the quoted phrase.

Ive lost the count ive negated this same statement: its repeated again and again despite its clearly wrong.

"plants reflect green light and so seem green to human eye.".

NO. "Plants reflect more green light than other colors and so seem green to human eye" would be the correct phrase. They seem very similar. But the first suggest all green light is reflected back and that absolutelly FALSE.

Cannabis reflects back less than 20% of total green light received, and mostly less than 15%. In general, difference between the most absorbed colors and green (the less one) is below 10%.

"green/yellow 500-650nm". I suppouse this is a typo. Yellow ends at 590nm, 600nm as max (but in color those wavelenghts are already amber)

"limited to no response". FALSE. 690nm produce less photosynthetic response than green at 550nm. Green photosynthetic response is similar to blue one. Green is the less efficient color producing plant growth, but difference with other colors is small. Yellow has a good photosynthetic effect, greater than blue, for example (ask HPS growers, which lamps emits mostly yellow-amber light).

I know im claiming in the desert, but i cant shut up when i see this off base statements posted again and again.

 

[purpledomgoddes]

690nm produce less photosynthetic response than green at 550nm.

550nm is on the declining slope of the photo responsive curve, w/ yellow being least responsive.

the curve goes from violet to blue to green to yellow to orange to red to far red.

there is CURVE, meaning that at different times of the day/night, they utilize different radiation wavelengths.

"green/yellow 500-650nm". I suppouse this is a typo. Yellow ends at 590nm, 600nm as max (but in color those wavelenghts are already amber)

proceeding from violet(400nm) to green(500nm) to yellow(600nm). gree and yellow are next to each other (visibly speaking), w/ green in the approx middle of the photo response (par) band.
the response curve is NON-LINEAR.

closest represntation would be the 'neutral' mh from sunmaster.

as far as green not affecting plants during dark, IF CONCERNED ABOUT INTERRUPTING DARK PERIOD - DON'T DO.

 

[purpledomgoddes]

gardeners use green light at night to navigate in area/maintenance/etc. if uncomfortable w/ this practice - abort/abandon/do do.
again, only providing option.

relevant to par/lighting response/etc - from many years of reseach.

no two scientif texts will say the same thing about almost anything, including lighting/etc. lots are trade secrets.

good place to start to RESEACH different practices is greenhouse engineering field. but rely on no single source.

not trying to provide false data - lots of it is disputed. sift through on own. don't rely on purpledomgoddes either. only conveying raw data for gardeners to investigate/apply on their own.

 

[Hydro-Soil]

Dialux Phillips catalog update link

Dialux Phillips catalog update link

Just found the link to the new Phillips catalog for the Dialux program
(thanks again Knna)

It's 80megs and you can find it HERE

I'm downloading it now.

 

[knna]

Glad you find it, Hydro-Soil. It has several hoods, for floros (T8, T5s) and all types of HIDs, with different light distributions.

I like to intro the room data, and place virtual planes (for what you ask results to the program) save it, and later installing different types of lamps and compare average light levels, how evenly they are distributed, how is the penetration for each, etc. Its an amazing learning experience about lighting.

purpledomgoddes, i know you posted it with the best purpose. I agree with you that many things arnt clear for scientistist, and are debatable.

Due that i choosed to correct those clearly wrong statements. What i posted is indisputed for any botanist (except maybe the 550 vs 690nm statement, which may be false applied to C4 plants) and have been proved many times.

Notice i didnt say anything about the use of green light to avoid disturb plant's night period. Green light is what affect less photoperiodic response, although it dont have anything to do with green reflectance, but to the sensibility of the different photoreceptors that trigger those responses (pythochromes and others). Coupled with the higher sensibility of the human eye for green, it makes it the best choice to work with plants without disturbing it. But still being so, if enough green light at enough intensity is used, it disturb night period.