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What is the point of deminishing returns? Min-Max Watts per sq foot.

I

Iron_Lion

Like the title says, what is the point where it becomes uselless to add more light per sqaure foot. I've got a tent with 50 watts per sq foot, would say 80 watts per sq foot be too much?

How many watts per square foot do you run?
 
H

hey.jude

New member
on a 4x4 table you get 1000 / 8 = 125watts per sq

it really matters about how much heat you can add to your space with out distrubing your plants
 
ItsAllOver

ItsAllOver

Devil's Advocate
I believe the point of diminishing returns with lights to be ~75 wpsf.
Keep in mind you are surely not going to get a correct answer, because distance from plants, type of light (600W are more efficient than 1kW), type of hood (aircooled? cooltube?) and other things play into it and more importantly, because no one has done any controlled experiments to figure this out, AFAIK.
I have this on my list of experiments I want to do, though... I'll be checking in here to see what people think...
 
CovertCrops

CovertCrops

Member
I run a 1k in a 4x4 tent which gives me 62.5 wpsf. I also run 2 3x3 tables with 600 over each of them, that gives me 66.6 wpsf. You can do ok with a 600 in a 4x4 which gives you 37.5 wpsf, but i want to stress the lower case ok, density will be lacking. Bring reflective walls right to your plants and you can get away with less. As with everything else that has to do with growing it is subjective. Looking over my post again it seems like I shoot for 60+ wpsf.
 
Hydrosun

Hydrosun

I love my life
Veteran
ItsAllOver said:
I believe the point of diminishing returns with lights to be ~75 wpsf.
Keep in mind you are surely not going to get a correct answer, because distance from plants, type of light (600W are more efficient than 1kW), type of hood (aircooled? cooltube?) and other things play into it and more importantly, because no one has done any controlled experiments to figure this out, AFAIK.
I have this on my list of experiments I want to do, though... I'll be checking in here to see what people think...
Click to expand...

I love a devils advocate & I'll disagree because I think you are not correct in this case. I have 2, 1Kw or 2,000w over 5'x10' so only 40w sqft and this is way more than enough. Also I will say that 1Kws being overdriven kick the crap out of 600w. Can a 600w do this 48" from the light?
picture.php


Peace, :joint:
 
unclefishstick

unclefishstick

Fancy Janitor
ICMag Donor
Veteran
i agree with hydro,after a certain point,without co2,it becomes a heat issue,strongly lit and too hot is worse for yield than maybe slightly under lit and perfect conditions,even with co2 you're better off with good temp/humidity than insanely bright
 
ItsAllOver

ItsAllOver

Devil's Advocate
Hell yea on advocating for the devil, but really you're just advocating your own opinion in this case. By this logic, you are the devil!
Anyway, how are you defining, "more than enough light?" Have you grown with more light in the same exact setup? Less light? You're surely right about the penetration of a 1k, in that respect they kick the crap out of 600w, but it's all system dependent. I believe the higher watts/lumen and closer light distance possible with 600w bulbs beats the 1k in SOG setups much of the time, but anyway...
We are, after all, talking about something with a lot of complexities and different variables that change everything.

And, as far as the "heat becomes an issue at high wpsf" thing, that is true, sometimes, but not always. Light, though, for sure. This is also light dependent.

Hmm, it'd be tough to set up an experiment for this that actually told you anything. You'd have to try it with many different light setups, HPS/PSMH, 600w/1k, different light distances, vertical?, air cooled?, bare bulbs?
 
Hydrosun

Hydrosun

I love my life
Veteran
Funny you should ask. Check the thread in my sig and you'll see that this isn't my first rodeo ;)

The Devil's Advocate deal is a play on the line under your name, I love my life; and wouldn't it be a wonderful world if Hydrosun was the devil?

Peace, :joint:
 
J

JackTheGrower

As has been written before light is one component in the system.

There are threads on this on this site that will inform.

Ran 1500 this medical grow.. Expensive with the fans going too.

I remember reading that a mature leaf can handle way more than 50 wpsf.. The nature of our lights makes getting close to ideal a guessing game.
The thing I tried this season was blended spectrum. It is an improvement.

 
GroDoc

GroDoc

Member
89w/sf with CO2

89w/sf with CO2

6 x 6 flowering room with 2 x 600 ventilated hoods and 2 x 1000 cool tubes = 3200w/36sf = 89w/sf. I'll let you know how they work out. peace
 
I

Iron_Lion

I forgot to mention, the reason why I asked all this is because I used to run a small grow box that had about 150W per sq foot, but my yeilds were never really all that spectacular. Plant quality was thru the roof, but yeild wasnt up to par with the amount of watts used. I think my biggest fault was not having enough plants in my grow space, and I should have had larger pots for the few plants I did have.

I recently got a new set up which I will be able to maximize with plant numbers with a nice even 50 wpsf, I'll be curious to see how it turns out. I'd like to get all this stuff straightend out before I go buy a 600 in a few months.

I'm looking to end up with a few LBs a year running 600 perpetual with a 250MH for veg/mothers/clones.
 
Hydrosun

Hydrosun

I love my life
Veteran
I pulled 49.5oz of Purple Kush from 50sqft under 2KW in 56 days. That equaled .5grms per square foot per day. I am trying to raise my grams per square foot per day, I think veg time will be the key NOT light per square foot. I only used 4 plants to get the 49.5oz. I now have 7 Purple Kush in the same foot print and we'll see.

This time:


Last time:


Peace, :joint:
 
CovertCrops

CovertCrops

Member
Hydrosun said:
I love a devils advocate & I'll disagree because I think you are not correct in this case. I have 2, 1Kw or 2,000w over 5'x10' so only 40w sqft and this is way more than enough. Also I will say that 1Kws being overdriven kick the crap out of 600w. Can a 600w do this 48" from the light?
picture.php


Peace, :joint:
Click to expand...


No, a 600 cant do that from 36" from the light. Wpsf is only part of it. I think the intensity of the bulb also has something to do with it. Its a lot harder to look at a lit 1k than it is to look at a lit 400. This intensity translates into those big dense bottom nuggs that 4's and 6's cant seem to produce, at least those are my thoughts on it. This debate is never ending so i figured i'd prove it to myself. Right now i am running a 3 x 6 room with 2 600's and a 4x4 tent with a 1k. both rooms are set up identically and I will be running the same strains through both rooms in order to see which yields better.

Hydro sun- those trees look great. Are you keeping a journal of the purple kush? I just moved some onto one of my tables.

peace, CC
 
VerdantGreen

VerdantGreen

Genetics Facilitator
Boutique Breeder
Mentor
ICMag Donor
Veteran
good thread. i would say the point of diminishing returns is around 50-60watts/square foot. you may get slightly bigger buds with higher intensity but it wont add up to the extra buds you could have got by lighting a bigger space.

my 250 cab is about 60 watts per square foot and if i built it again i would make it slightly bigger with about 50-55 watts/sq ft.

V.
 
G

guest 77721

I'll agree with 50w/sqft grows nice buds and in a growroom it makes sense to trade grow area for lighting intensity, especially if the lighting is expensive.

In a small growbox it's easy to put more than 50 w/sqft by adding a light or upping the wattage. CFL's are cheap and a well built growbox can easily run at 100 w/sqft.

What's the maximum lighting the plants will take while keeping temps reasonable?

How much light intensity do you need to double the yield?
 
ItsAllOver

ItsAllOver

Devil's Advocate
redgreenry said:
What's the maximum lighting the plants will take while keeping temps reasonable?
Click to expand...

Depends on the type of lighting used, volume of grow room, aircooled/not, fan size, ambient temps, and distance of plants from lights. That's pretty much an unanswerable question without a lot more info.

redgreenry said:
How much light intensity do you need to double the yield?
Click to expand...

Same answer.
What did you mean by those questions?
 
sorcival

sorcival

Member
Always remember that the big HPS in the sky has unlimited lumens and watss per sq ft.
BUT...just for rememberance sake, I recall a thread over on OG way back when, where
the light was measured in lumens per sq ft. The consensus at that itme was that 4,500
lumens per sq ft was the bare ass min. for a decent harvest without stretchy shit and
that the Ideal was about 10,000 lumens per sq. ft. for a good tight nug grow.
Im sorta stoned so my memory might just be a tad off, so feel free to correct me, k?
 
ItsAllOver

ItsAllOver

Devil's Advocate
sorcival said:
Always remember that the big HPS in the sky has unlimited lumens and watss per sq ft.
Click to expand...

Unlimited lumens and watts from the sun per square foot on the ground of earth? Figure out how to do it and the energy crisis is solved! :woohoo:
Just fyi, the sun emits differing amounts of watt-converted energy depending of your location on the earth, but where I am it's about 1kW/ square meter. Don't know the lumen number, though.

That's cool about the OG thread. If only we still had that resource, too.
 
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