Hypothetical spacing questions

[_Dude]

If you had 10 600w lights and wanted to do a SOG grow and space wasn't a big concern. You're going to use a 4' wide tub but you can make it as long as you want and space the lights however you want lengthwise. Would you put each light over a 4x4 area, or would you pack them closer, say three or two feet apart? What spacing do you think would yield most with a good CO2 generator set up? Use whatever mix of MH and HPS you want to make your argument. Wondering how to maximize grams per watt given a fixed number of lights and flexibility on spacing.

 

[FrankRizzo]

600's work better in an area of 3x3, you'd have 66.6w psf per bulb. If you did 4x4 you'd only have 37.5w psf per bulb. 1000's are more suited for 4x4.

 

[_Dude]

I'm kinda moving beyond the PSF and coverage issues here. It's a fixed number of lights with a fixed wattage, and just wondering how to space them lengthwise for best coverage to maximize yield. Yes, closer would mean better in terms of PSF, but that doesn't tell me much. I know buds would be denser if a closer spacing is used, but I don't care about that so much as max yield.

I'm not worried about penetration so much, since these will be small SOG plants.

I guess what I really would like is a graph showing light (watts or lumens) per square foot vs yield in controlled experiments. Obviously there's got to be a sweet spot, all else being equal.

 

[Quazi]

Actually, the "watts per square foot" measurement seems like it would be important if you are trying to figure out the maximum yield from the space.

Here's a visual
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Let's assume, for argument's sake, that you get 0.5 grams per watt.

Assume your 600W is in the middle of that 4x4, you're getting 37.5W per sq. ft. That means that each plant is receiving 37.5W worth of light. That means you have the potential to get 18.75 grams per plant. That's roughly half an ounce from a single plant.

You said you had 10 lamps. So that means you'd have to have 160 plants to care for to yield 3,000g. That's a lot of damned plants not to mention, it's over the magic 99 by a considerable amount.

Now, let's look at a 3x3 setup.
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Assuming the same as above, you're getting 66.7W per sq. ft. Since you're not really at the point of diminishing returns here, we'll assume that you can pump the same half gram per watt our of your plants. Now each plant will be yielding 33 grams. That's over an ounce per plant which is not too much to hope for at all.

With 10 lamps, that means you've got 90 plants to care for and yield 3,000g.

Taking care of 160 plants vs 90 plants for the same yield? Yea, maybe watts per sq. ft is worth looking at when considering the setup. I'm not discounting what you said above, I'm just trying to point out that it is a helpful measurement when you're looking at the grand scheme of things.



It sounds like you're knowledgeable enough on the subject so I can't wait to see what happens.

-Q

 

[_Dude]

It sounds like you're knowledgeable enough on the subject so I can't wait to see what happens.

No! I'm reading Cervantes book and totally reevaluating everything. I thought 1ks were best but all the people who said 600s are better were right. I'm researching how to do this setup right.

I'm still reading your post but I wanted to make that clear.

I still would like to know a "sweet spot", by that I mean what's the most efficient watts PSF lumens PSF or whatever, but I'll throw another question on the pile:

If I do a closed system with CO2, what's the best reflector setup? On one hand, Cervantes is really pushing these adjustable wing reflectors. On the other, air-cooled is obviously the way to go if you want to get the lights as close as possible to the plants. I didn't used to give much thought to anything but air-cooled because I was planning with 1ks. Now I'm planning on 600w lamps and wondering what I should do because it seems that air-cooled lights don't reflect as efficiently as the adjustable open types that have reflectors underneath the light too, to protect from hot spots. The CO2 adds a complication because you can't just vent the air out constantly, so it seems air-cooled is still the way to go but I'm open to suggestions.

 

[_Dude]

Actually, the "watts per square foot" measurement seems like it would be important if you are trying to figure out the maximum yield from the space.

Here's a visual
[][][][]
[][][][]
[][][][]
[][][][]

Let's assume, for argument's sake, that you get 0.5 grams per watt.

Assume your 600W is in the middle of that 4x4, you're getting 37.5W per sq. ft. That means that each plant is receiving 37.5W worth of light. That means you have the potential to get 18.75 grams per plant. That's roughly half an ounce from a single plant.

You said you had 10 lamps. So that means you'd have to have 160 plants to care for to yield 3,000g. That's a lot of damned plants not to mention, it's over the magic 99 by a considerable amount.

Now, let's look at a 3x3 setup.
[][][]
[][][]
[][][]

Assuming the same as above, you're getting 66.7W per sq. ft. Since you're not really at the point of diminishing returns here, we'll assume that you can pump the same half gram per watt our of your plants. Now each plant will be yielding 33 grams. That's over an ounce per plant which is not too much to hope for at all.

With 10 lamps, that means you've got 90 plants to care for and yield 3,000g.

Yeah, but I want absolute minimum veg time. I'd go with no veg, but that seems too radical and means I'd have to pack them in 9 per square foot?

Not worrying about the magic 99.

Taking care of 160 plants vs 90 plants for the same yield? Yea, maybe watts per sq. ft is worth looking at when considering the setup.

Yeah, this is totally the kind of thing I'm wondering about, but I'm thinking with SOG (1 week veg) the plants won't need much minding. And yeah I spoke in haste above about watts PSF, what I meant was, I need more than a simple minimum threshold for watts PSF, and something more like a graph showing where the best efficiency is.

 

[Quazi]

Couldn't find this available in a copy-paste format at work so I'll type it out for ya 'cause I'm taking a break at work.

If you wanna go quoting Mr. Cervantes then let's see what he has to say on the subject when asked. Marijuana: Jorge's Rx:

"If you're growing the right strains indoors, and you've got 65 watts per square foot of HPS light, can you increase the yield by spreading the plants out so you've got only 50 watts per square foot?

That would be 30% more area, but 23% less light. I know HIGH TIMES says the yield would be about equal, with at least slightly better quality with the brighter light, but whenever you guys discuss this you're just about always talking about the difference between 20 and 40 watts per square foot.

Obviously there's a point of diminishing returns in cramming the plants as close together as possible. Otherwise, why not use HALF the area, and grow under 130 watts per square foot? Because the plants can only use so much light AND the closer together the plants are, the more they block each others' light.

...part about light movers...

Yeah, it's true that 70 or 80 watts per square foot will grow much bigger individual buds than 50 watts per square foot, but it's the TOTAL yield that's important. Besides, my experience is that huge buds aren't the way to go. Light only penetrates so far into the interior of a huge bud. The interior of huge buds tend to be leafy, and compared to leaves growing on the surface of buds, interior leaves tend to be lighter in color (having less chlorophyll) and more "ruffled" (less flat), and most importantly have FAR fewer glandular trichomes."

...and the master's response:

"Let's see, 65 watts per square foot of HPS light that would be one 1000w HPS hung over an area that measures about 4 x 4-feet, and 50 watts per square foot would be one 1000w HPS over a 4.5x4.5-fot area. Dude, either way the light is blinding!

...part describing how 600W is the best lumens per watt...

Your plants will produce less leaf and more bud under 65 watts-per-square foot, but a very similar net harvest of dry buds. Watts per square foot does not account for how much light is received by plants. Other factors such as how far the lamp is away from the plants, the efficiency of the lamp and the reflector and the point source of illumination are not factored into the equation either.

After doing the research on my book, Marijuana Indoors: Five Easy Gardens, I'm not in agreement with the yield being "about" equal when the proper lamp is used. In fact, the yield of dried bud per watt every 60 days drops like a rock! A healthy yield with 1000w bulb is two pounds (908 grams) in the area. Divide 908 by 1000 to find grams per watt (GPW). 908/1000 = 0.908 GPW. Changing the bulb to 600 watts will drop the watts per square-foot to 40 and cause the harvest to fall about 20 percent, (726 grams) but the grams per watt increases to 1.36 (726/600 = 1.21 GPW) about 20 percent more.

The big part to notice is at the end where he mentions that 1000W to 600W only drops the harvest by 20%, not the expected 40%.

Just some additional info for ya.

-Q

 

[_Dude]

Yeah that's good stuff Quazi, big thanks for taking the time to type that out (above and beyond the call of duty!).

 

[FrankRizzo]

I know buds would be denser if a closer spacing is used, but I don't care about that so much as max yield.

Denser bud=more plant material=more weight.

Edit-I was also reading in another thread that 75w psf is closer to what you need to make co2 useful. Not sure how true that is (gonna try and find out) but if that is the case than your lamps are gonna have to be even closer together to get your w psf numbers higher.

 

[_Dude]

Yeah, I was wondering about the increased light utilization with CO2 also, thanks.