Cob/plant distance

Yeah, i know this have been asked a lot of times, but i find that the aggregate answers have to broad range, from 3 inches to 2 feets. and most answers lack the proper context, how many cobs? watts per cob? which cob model? lenses? area?

so, how do you run your setup? i'm new in the cob world so any experience and lesson from someone with more time in the game is well appreciated.

as for me, i'm running 150w, 4 citizen CLU048-1212c4 gen6, at around 37,5w each, in a 2x2, no lenses, but with mylar. placed at a distance at around 16 inches. is that ok? to close, to far? first grow with cob.

thanks

garyocampo said:

Yeah, i know this have been asked a lot of times, but i find that the aggregate answers have to broad range, from 3 inches to 2 feets. and most answers lack the proper context, how many cobs? watts per cob? which cob model? lenses? area?

so, how do you run your setup? i'm new in the cob world so any experience and lesson from someone with more time in the game is well appreciated.

as for me, i'm running 150w, 4 citizen CLU048-1212c4 gen6, at around 37,5w each, in a 2x2, no lenses, but with mylar. placed at a distance at around 16 inches. is that ok? to close, to far? first grow with cob.

thanks

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I got around 6-700w of mixed luxeon 1211's with a smattering of vero 29's but averaging 50w per sq foot and hung all different heights, I have found that the light emitting surface type leds/cobs have such a directional beam without optics they are just extra cost and hassle, cob spacings seem relatively unimportant just average wattage over the area and height is again fairly unimportant, they seem to defy the inverse square law of hps and will work if strung way over the crop, i aim for a foot or so but always consider the 120 degree cone of primary radiance from each cob and ensure maximum plant/light cone matching but frankly i could leave em high and doubt it would make a spot of real difference providing my walls are highly reflective. pm me if ya wanna see my rig. Anything less that 4 inches under anything more than 40w will bleach the tops but raise the light and they will recover, less than an inch could risk literally incinerating the bud and smoke damaging the cobs delicate silcone surface, tho if a cob does get burn marks let it cool and wipe with a soft cloth and plain water.

75W cobs and i try to keep an even canopy 18" below them

freemanjack said:

they seem to defy the inverse square law of hps

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thats because of the array effect. move 12" out from under a cob and youre getting half the light from one cob and half from another

better light distribution is a huge reason why peopel do well with cobs

CobKits said:

thats because of the array effect. move 12" out from under a cob and youre getting half the light from one cob and half from another

better light distribution is a huge reason why peopel do well with cobs

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I wasn't suggesting the inverse square law did actually not apply (er, physics), I see what the light meter says, it just don't seem to make a toss of difference, greengenes mentioned he had similar experience too, i suspect it is due to the very low levels of scattering and the directionality of LES devices and no, its not my confusion over intersecting light cones coz my single v29 veg light has the same effect. All that said, i still hang em as low as the plants will take, hps habits are hard to break, just not actually sure it makes any meaningful difference to final flowering, by then my girls are huge anyway so its more about can i get em high enough!

Just Read your plants........ they will tell you if the cobs are to close.

Good luck

I have had bleaching probs at 12 inches above canopy level with cree 3590s at full power. Bit of stress at about 18". Been trying.to keep mine around 22 inches....

freemanjack said:

by then my girls are huge anyway so its more about can i get em high enough!

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its more about if they can get you high enough

garyocampo said:

i'm running 150w, 4 citizen CLU048-1212c4 gen6, at around 37,5w each, in a 2x2, no lenses, but with mylar. placed at a distance at around 16 inches. is that ok? to close, to far? first grow with cob.

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It's too far. Fine for veg but when the buds start putting on bulk you want to get them in the 6-8" range. Even with 90 degree reflectors or lenses, 6" above the canopy would be the proper light spread with one cob per square foot. Coverage area divided by 2 gives ideal hanging height to minimize the amount of light hitting the walls. Intensity is another matter, but at 37 watts you'll probably be fine at that height.

Get them as close as you can. Ideally you're bold enough to find out what is too close. That way you know what is just right.

freemanjack said:

...... I have found that the light emitting surface type leds/cobs have such a directional beam without optics they are just extra cost and hassle, .......

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nice info. I didn't fully understand this part though. do you find lenses to be a waste or important to have?

CobKits said:

75W cobs and i try to keep an even canopy 18" below them

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wow, you run them hotter than i would expect from you.

Rahz said:

It's too far. Fine for veg but when the buds start putting on bulk you want to get them in the 6-8" range. Even with 90 degree reflectors or lenses, 6" above the canopy would be the proper light spread with one cob per square foot. Coverage area divided by 2 gives ideal hanging height to minimize the amount of light hitting the walls. Intensity is another matter, but at 37 watts you'll probably be fine at that height.

Get them as close as you can. Ideally you're bold enough to find out what is too close. That way you know what is just right.

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thanks, today i lowered to 12", i'm going to lower slowly trying to find the G spot.

garyocampo said:

wow, you run them hotter than i would expect from you.

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rig is a year old. next one is in the works and will be uber efficient. this one does very fine for me!

I also think Cobkits needs to explain why he isn't running cobs at 10w heat sinking them with aluminum cookie sheets.

Maybe the big heat sink manufacturing cartel has a hold on him!

Rahz said:

It's too far. Fine for veg but when the buds start putting on bulk you want to get them in the 6-8" range. Even with 90 degree reflectors or lenses, 6" above the canopy would be the proper light spread with one cob per square foot. Coverage area divided by 2 gives ideal hanging height to minimize the amount of light hitting the walls. Intensity is another matter, but at 37 watts you'll probably be fine at that height.

Get them as close as you can. Ideally you're bold enough to find out what is too close. That way you know what is just right.

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What about 6x 1212 at 37W in 80x80 cm tent?

garyocampo said:

nice info. I didn't fully understand this part though. do you find lenses to be a waste or important to have?.

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I junked lenses and reflectors after my first few builds. so little light comes out sideways the reflectors were more or less pointless and lenses just focus already high intensity light into even more intensity, I just use a good quality white/mylar reflective sheeting on all my walls, white side out (if you hold the sheet up to the light, less comes thru the white side than the silvered side showing better reflectivity from the white surface). My girls all have a good 2-3ft of fully penetrated canopy, short internodals and superb plant health/performance. Why complicate everything light + soil + plant + biology = good weed zero labour.

Solution: More 20w cobs over grow panel. Better coverage...no burn.... Great penetration. I have one diy like that.
9 cobs all together pulling 150w. So 30 less than labeled. I use in 2.6x2.6....