Have any of you DIY COB Growers finished a crop under 1000W DE HPS? - POLL

BOBBY_G said:

we'll see. im not as amazed with the CMH as i thought i would be but maybe im just running too hard. (4) 315s in a 5x5 is throwing down 1000-1300 ppfd at 20-24"

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Running HID hard... Hadn't seen that one before. But yeah, you basically are doing just that. The more you spread out the light, the more space for plants/buds. And the higher the ppfd, the less extra yield for every increment. If space is not a limit but you got like 1500 ppf to spend, you get higher gpw from running 750ppfd than 1500. It'll be more leafy and relatively more branches under 750 than 1500.

In fact, @Rahz is not correct with his 1 par = 4 gram "basic math". It omits an important factor, it depends on the space used. See ppfd/temp graph from uni of Utah...

That phenomena seems to play more a role now with replacing hps with cmh than led though, as led builders don't tend to go lower than hps (anymore). Replace a 600w on 3x3 with a cmh 315 and you will increase the gpw, even if you get less grams in total.

Sativied said:

With emphasis on 'basic'. And in a fictional situation where nothing else than par/w eff of the light source matters. For a more realistic comparisson however it's not that simple and more to it then running cobs soft to reduce power usage and increase par/w efficiency.

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Running the CXB3590 at 50% efficiency is accomplished at 2.1 amps. The nominal current is 2.4 amps. It's not exactly running soft at 2.1 amps. I would consider soft 1.4 amps - .7 amps and below. But then we're talking 56 and 64% efficiency. And when it comes to efficiency, it's all just a means of determining PAR watts (and how many actual watts it takes to get there), IE- how many photons are coming down and the electric bill. All the other parameters between 2 full spectrum light sources are minor unless we're splitting hairs. Funny though, it wasn't that long ago that power was all that mattered according to the HID proponents.

Sativied said:

In fact, @Rahz is not correct with his 1 par = 4 gram "basic math". It omits an important factor, it depends on the space used. See ppfd/temp graph from uni of Utah...

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Sure there are other parameters, but if you adjust for one light you adjust for the other. Modify the parameters and the results may be slightly higher or lower, but that has nothing to do with an advantage for a particular light source.

@Sativied Here's the PPFD data you cited, converted to bar format. Nothing I'm not aware of.

Sativied said:

Running HID hard... Hadn't seen that one before. But yeah, you basically are doing just that. The more you spread out the light, the more space for plants/buds. And the higher the ppfd, the less extra yield for every increment. If space is not a limit but you got like 1500 ppf to spend, you get higher gpw from running 750ppfd than 1500. It'll be more leafy and relatively more branches under 750 than 1500.

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yeah 5x5 is an awkward space to fill evenly. i think i might snag two more cmhs and do 6 315s in a 5x9 which would be perfect

BOBBY_G said:

yeah 5x5 is an awkward space to fill evenly. i think i might snag two more cmhs and do 6 315s in a 5x9 which would be perfect

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or 4 315s and a dozen 2700K cobs. that sounds like oozy huge goodness waiting to happen

if its one thing COB offers its versatility

blue up your HPS rig with some uber efficient 5000K
red out your CMH with some low K cobs that are still more efficient than any hid

both of which come in 25-250W increments that you can place around your grow to your hearts delight

BOBBY_G said:

yeah 5x5 is an awkward space to fill evenly. i think i might snag two more cmhs and do 6 315s in a 5x9 which would be perfect

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That's a lot of lights for that space, I run 3 600 watt HID lights in a 5x10, covers from wall to wall.

BOBBY_G said:

or 4 315s and a dozen 2700K cobs. that sounds like oozy huge goodness waiting to happen

if its one thing COB offers its versatility

blue up your HPS rig with some uber efficient 5000K
red out your CMH with some low K cobs that are still more efficient than any hid

both of which come in 25-250W increments that you can place around your grow to your hearts delight

Click to expand...

Orrrr just place a MH between your HID lights....its so blue andddd actually produces UV light unlike COBs.

yeah but so inefficient

BOBBY_G said:

yeah but so inefficient

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But costs 1/10th the price and has a much larger coverage pattern.

Yodaweed said:

That's a lot of lights for that space, I run 3 600 watt HID lights in a 5x10, covers from wall to wall.

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have you measured it? i have to get a pretty good distance from my ac/de (arguably the best) reflector to get good measurements at 2.5' from center (ie 5' spacing)

right now i have 2 ACDEs in a 5x9 (with the better 'side' throw on the 5' dimension and the poorer 'axial' throw on the 4.5' dimension. again it takes 36" to get good coveage. with cobs it would be like 12-24"

Yodaweed said:

But costs 1/10th the price and has a much larger coverage pattern.

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yes im aware of the old adage "you get what you pay for"

BOBBY_G said:

have you measured it? i have to get a pretty good distance from my ac/de (arguably the best) reflector to get good measurements at 2.5' from center (ie 5' spacing)

right now i have 2 ACDEs in a 5x9 (with the better 'side' throw on the 5' dimension and the poorer 'axial' throw on the 4.5' dimension. again it takes 36" to get good coveage. with cobs it would be like 12-24"

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Plants grow from wall to wall so seems to cover the area fine. My lights are about 2 or 3 feet above the canopy.

i think im gonna take one of the 315s out of the 5x5 tent and put it between the 2 DEs in the 5x9 and drop them from 1100W each to 850

BOBBY_G said:

yes im aware of the old adage "you get what you pay for"

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With cannabis I don't agree, the same methods can be done for lesser costs. Like I don't buy ANY premade nutrients, I make that shit myself costs 10x less and I get soooo much more and I actually get ORMI listed ingredients instead of random crap I have no idea what it is.

Yodaweed said:

Plants grow from wall to wall so seems to cover the area fine. My lights are about 2 or 3 feet above the canopy.

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as i said 3'

do you have a light meter? i was shocked by my actual coverage when i got mine

The "you get what you pay for" idea is something the grow store guys would say.

BOBBY_G said:

as i said 3'

do you have a light meter? i was shocked by my actual coverage when i got mine

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Yes I do, I get 10,000 lux at 3 feet in the corner of my tent .

BOBBY_G said:

or 4 315s and a dozen 2700K cobs. that sounds like oozy huge goodness waiting to happen

if its one thing COB offers its versatility

blue up your HPS rig with some uber efficient 5000K
red out your CMH with some low K cobs that are still more efficient than any hid

both of which come in 25-250W increments that you can place around your grow to your hearts delight

Click to expand...

So many options they have you talking to yourself! Happens to me all the time...

Yodaweed said:

Yes I do, I get 10,000 lux at 3 feet in the corner of my tent .

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can you translate that to plant numbers? 10000 lux looks like 130 ppf based on this conversion (for hps)

http://www.apogeeinstruments.com/conversion-ppf-to-lux/

@BOBBY_G I just tested my COB LED rack and it worked fine. I split the modules into two groups of a dozen and plugged them in separately. Did it several times, no issues, I'll run two timers set a few moments apart.