Cob/plant distance/Luxmeter/4 COB'S per plant @35Watt each, 140W total....

Salah82

Active Member
First time grow with DIY COB'S, looking for the right amount of light and distance measured with a fluxmeter.

2x2'.....one plant.......4 Luminus CXM 22 3500K 90CRI @ 35 Watt each......140Watts total.

Need help!

Thank you
 

Salah82

Active Member
First time grow with DIY COB'S, looking for the right amount of light and distance measured with a fluxmeter.

2x2'.....one plant.......4 Luminus CXM 22 3500K 90CRI @ 35 Watt each......140Watts total.

Need help!

Thank you
  • Clones and seedlings: 5,000–7,000 lux
  • Vegetative growth: 15,000–50,000 lux
  • Flowering: 45,000–65,000 lux
  • Maximum recommended amount of light: 75,000 lux
???????????????
 

wietefras

Well-Known Member
Height should be good at around 20cm / 8" (two thirds of the distance between the COBs).

140W is perhaps a bit much for such a small smap

Clones and seedlings don't need such a big light, but once they look like decent plants (say 6 internodes) you can blast them with full power.
 

Salah82

Active Member
Height should be good at around 20cm / 8" (two thirds of the distance between the COBs).

140W is perhaps a bit much for such a small smap

Clones and seedlings don't need such a big light, but once they look like decent plants (say 6 internodes) you can blast them with full power.
Anyway to measure with the fluxmeter to adjust the light for optimum results?
 

wietefras

Well-Known Member
With a light meter you can try measuring a matrix of measurements at the desired height. The darkest measurements should at least have 80% of the intensity of the average (apart from some exceptions like say in the corners).

lux measurements from that table you can measure with a lux meter. Again I would work with the average value though.
 

InTheValley

Well-Known Member
at 14 inches, you should see 20,000 lux directly under the COB@35 watts (just checked) or about 335 PAR.

How far apart are your cobs? ( spacing between )

with all 4 of mine on, at 35W each, I get 20,000 lux at 24 inches from light. in a 2x2 you will have pretty great coverage fro veg .. ( 2x3500K and 2x4000K )
 
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Salah82

Active Member
at 14 inches, you should see 20,000 lux directly under the COB@35 watts (just checked) or about 335 PAR.

How far apart are your cobs? ( spacing between )

with all 4 of mine on, at 35W each, I get 20,000 lux at 24 inches from light. in a 2x2 you will have pretty great coverage fro veg .. ( 2x3500K and 2x4000K )
Yeah brother InTheValley.....i got 4 cobs in a 2x2' area.......1 cob per square foot. 35 watt each.....so you say 24 inches (60cm from the plants).....since i never grew with those beauties.....can i put them any closer then the 24 inches or would that do harm to my plants?!
 

InTheValley

Well-Known Member
Yeah brother InTheValley.....i got 4 cobs in a 2x2' area.......1 cob per square foot. 35 watt each.....so you say 24 inches (60cm from the plants).....since i never grew with those beauties.....can i put them any closer then the 24 inches or would that do harm to my plants?!
Man, ive put my plants pretty close and never had problems. Mine are at 15 days from seed now and I have them at 35,000 lux
 

Rahz

Well-Known Member
Stick your hand close under an emitter. Notice how it bleaches the color of skin. Lower your hand until it doesn't look bleached, just bright. That's the minimum distance to canopy. I haven't used CXM22s but at 35 watts I'll guess it will be around 8-9 inches. You can go lower as long as the emitters aren't directly over the top flowers. I've actually had flowers sticking up through the frame of my lamp before.
 
Lux isn't going to help you at all. You need a PAR meter, and they are very expensive. PAR meters measure PHOTOSYNTHETIC ACTIVE RADIATION, or the
light that your plants can use. Some of this light is hardly, or not visible to the human eye. It's why your cob looks white/orange when it is really full spectrum. While COBs do beter with lux meters than blurple LEDs do, LUX still doesn't mean shit when it comes to growing plants so I don't know why people think otherwise.
 

Salah82

Active Member
Lux isn't going to help you at all. You need a PAR meter, and they are very expensive. PAR meters measure PHOTOSYNTHETIC ACTIVE RADIATION, or the
light that your plants can use. Some of this light is hardly, or not visible to the human eye. It's why your cob looks white/orange when it is really full spectrum. While COBs do beter with lux meters than blurple LEDs do, LUX still doesn't mean shit when it comes to growing plants so I don't know why people think otherwise.
There is a way to calculate that with the flux
Lux works fine, you don't a PAR meter. It's a simple translation from lux to PAR. For warm white leds, divide lux by say 70 to get an indication of PAR.

Besides, the plants can deal with 250 to 2000umol/s/m2. Just an estimate for intensity really is more than enough.
So where exactly do i measure the flux.....with a cheap fluxmeter? top of the plant right?!
 

InTheValley

Well-Known Member
Man, A PAR meter is needed if there is no idea of the spectrum of the COB, but in this case of the Luminus, we know the spectrum, and we know the JPW, and we know it has the PAR the plant needs. SO, you can use the LUX meter to simply check the intensity in your grow space to make adjustments.

I have a Lux meter, I drilled a hole in the cap, then i calibrated ( used scotch tape in layers ) till I got the conversion factor of lux/par, and now, it works just like a PAR meter, as per my calibration.

and from what ive seen, the Hydrofarm PAR meter does nothing more then the conversion of the lux anyways. $125+ is a waste of cash that can be used for other things at the end of the day, when you can simply get a great idea of PAR with this Lux meter hack.
 

InTheValley

Well-Known Member
16 days from seed, 12/12 from seed. Topping today, should show sex in 4-5 days, pull males, flip to 18/6 for 3 weeks. then going to 6 on, 10 off experiment. These are watered 8 times a day in cocolocoday16veg-Sun1.png day16veg-Sun2.png
 

Salah82

Active Member
300 watts @ 18-20 inches
I just measured with a cheap luxmeter and id have to run my 4 cobs @ 293watts to get me 50.000Lux?!

Id loike to make a full cycel run with just 35-50 watts per cob.......but it seems to me that i wouldnt have enough lux, light hitting my plants???!
 
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