sq ft vs cu ft wattage

The Loafter

Well-Known Member
assuming my 4lx4wx6 tent needs 480 watts (30 watts/ sq foot), would the same tent on its side - 6lx4wx4h still need just 480 watts
 

ilovereggae

Well-Known Member
sure it isn't. but photons bounce apparently. less headroom to bounce off
I follow your thinking to a degree. I am about to do the same w 2 tents that I have that are 2x3x4.5. flip sideways so they are 2x4.5x3 so I can put them on top of each other on a rack. and get 16sf of grow out of 8sf of floor space.

With that said my thinking is I really need to spread out my diodes to make this work. which will allow fixture to be closer and get the light to all plants instead of relying on a slight spread and higher hanging height. which results in more efficient diodes that are in sum total getting more photons to the plants.

my thought is we will stuff need at least 30wsf based on footprint. but maybe you can get away with less than that if you are doubling up on diodes to compensate for the larger square footage but lower overall height? i don't know.
 
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The Loafter

Well-Known Member
but my thought is we will stuff need at least 30wsf based on footprint. although less efficient older diodes should balance things out. dont know how scientific it is. but seems to make sense to me.
Im assuming in my scenario same watteage for cu ft. so 480 watts at 4x4x6 = 4x6x4 at 480 watts

goes from 30 w/ft to 20w/ft

does anyone have some dialux ies files i can play with. I haven't tried yet.

beer delivery came at 7:15 this morning btw.
 

ilovereggae

Well-Known Member
Im assuming in my scenario same watteage for cu ft. so 480 watts at 4x4x6 = 4x6x4 at 480 watts

goes from 30 w/ft to 20w/ft

does anyone have some dialux ies files i can play with. I haven't tried yet.

beer delivery came at 7:15 this morning btw.
what led modules are you using? strips or boards?
 

The Loafter

Well-Known Member
not running much right now. shameful really. i have 3500w ish of modules. or 5400 lol. the tent i have on its side 4x6x4 has 8 knockoff 304s and 2 legit qb 324s. i pulled the plug in may or june working too much and they grew into the lights.

edit: i neglected my garden :'(
 
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The Loafter

Well-Known Member
Again

It's the footprint or SF the light covers. Lights don't go UP, they project down

4x4 = 16sf
4x6= 24sf
they project at 120degrees. assuming the light faces down then yeah it projects down, and sideways.

in a vertical grow ( stacked grow areas with overhead lighting) is square footage the only factor when considering lighting power?
 

ilovereggae

Well-Known Member
Again

It's the footprint or SF the light covers. Lights don't go UP, they project down

4x4 = 16sf
4x6= 24sf
i get that, lets make a simpler comparison tho.

we can agree that if you take one QB288 running at 3200ma with say a hanging height of 2 ft, and instead run it into 2 QB288s at 1600ma each, the spread is better, the diodes are cooler and you can probably drop to 1ft away from canopy. i know this works because I have done it, and really that is what the Rspec Scorpion is doing right? Running the same wattage to 6 boards instead of 4 so you get a better spread and can run closer to the canopy. HLG even markets it as being better for vertical rack style grows.

so with that said, I think what @The Loafter is getting at, is at some point there is diminishing returns bc the light doesnt point straight down actually at all. it bounces at 120 degrees and will hit the walls etc.

i don't know if i agree that you can exclusively go by cu ft instead of sf. but i do think that maybe if you went with even more diodes you could get away with slightly less wattage.

I think 30 w/sf is based on running current gen lm301b/h at close to or max wattage to hit the magical 200 lm/w. but i think there is other ways to come out with the same number of photons based on fixture design. for instance i just bought a shitload of V1 boards instead and run them at 1A. I dont have enough knowledge to do all the math but there has to be some way to calculate the sf # based on total diode count and hanging height.

also think that inside a tent vs open space will affect the outcome as well.
 

ilovereggae

Well-Known Member
In theory yes

But dimmed down you won't get the penetration as you will at full blast and a bit higher up
isn't it all relative though bc theoretically you get more even coverage across the whole canopy with more diodes running at less current? which is why strips are considered the best possible choice atm.

i guess the laymans terms way i guess I think about it is HID was one big bulb. Cobs got us to a say 6 intense points of light spread over the canopy. Current gen LEDs got us to 100s, and now depending on your design, thousands. it might be anecdotal but from what i've seen spread and intensity matters even more than color spectrum. so i dont know. i feel like we all still have a lot of experimenting to do.
 

The Loafter

Well-Known Member
i see 480 being a bit low even on a 4x4. another 10% would be nice but w/e.

its the same volume anyhow, and there would be less headroom to waste energy or reflection.

assuming its just sq ft that matter. do we really need 4x4x6 tents or can we save waste and use 4x4x4 instead?
 

ilovereggae

Well-Known Member
i see 480 being a bit low even on a 4x4. another 10% would be nice but w/e.

its the same volume anyhow, and there would be less headroom to waste energy or reflection.

assuming its just sq ft that matter. do we really need 4x4x6 tents or can we save waste and use 4x4x4 instead?
hmm 4ft high and 4 foot deep is going to be hard to get to the plants in the back.

i do think temp + rh will be easier to control inside smaller spaces. part of what appeals about it to me.

i think airflow will be harder to manage without the volume of air inside the tent to help dissipate heat and get a nice vortex going, without causing windburn to the plants.

i think 2x4x4 tents on racks is the future. 2x4x3 if I can prove to myself that I can get away with 36" in flower.
 
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