Calling all COB experts. Advice needed

K

kingCharles

New Member
Noob here trying to find my way through a current (and first ever) grow.

I figured I should share what I've put together so far and see if I've screwing anything up. I did basically just throw this all together after researching a bit on here.

Setup:
4 CXB3590 36v 3000k
MW HLG-185H-C1400A driver
KB 100mm 80degree reflectors
10.000" profile x 20" heatsink(heatsinkusa) + 120mm cougar pc fan
Pandafilm tent 32" x 20" x 60" high

Due to the very small size of the tent, I have the driver running at the lowest setting for .590ma. Would my calculations be correct in that I'm pulling about 21watts per cob? Given that I'm in going into flower now, I'm unsure if this is too little/much par watts.

I can say for veg this worked out quite well. Lots of healthy growth, but now that I'm switching to flower I'd like to make sure I'm doing the right thing moving forward.

How much current do you guys think i should send to these, and at what distance from the canopy?

Here's a couple shots of the setup



 
Airwalker16

Airwalker16

Well-Known Member
kingCharles said:
Noob here trying to find my way through a current (and first ever) grow.

I figured I should share what I've put together so far and see if I've screwing anything up. I did basically just throw this all together after researching a bit on here.

Setup:
4 CXB3590 36v 3000k
MW HLG-185H-C1400A driver
KB 100mm 80degree reflectors
10.000" profile x 20" heatsink(heatsinkusa) + 120mm cougar pc fan
Pandafilm tent 32" x 20" x 60" high

Due to the very small size of the tent, I have the driver running at the lowest setting for .590ma. Would my calculations be correct in that I'm pulling about 21watts per cob? Given that I'm in going into flower now, I'm unsure if this is too little/much par watts.

I can say for veg this worked out quite well. Lots of healthy growth, but now that I'm switching to flower I'd like to make sure I'm doing the right thing moving forward.

How much current do you guys think i should send to these, and at what distance from the canopy?

Here's a couple shots of the setup



Click to expand...
You should defoliate that shit. And definitely turn up your driver all the way up for flower for sure.
Btw, I like your design. Sweet choice on the 10" sink. But you're only cooling the middle 1/3 of your fins. You oughtta get yourself a 10" case fan for it or switch to 2-140mm ones side by side. You want a fan above any fins that have heat sinking in to them...
That way you'll have no problems cranking out the 50watts each they're capable of hitting with that driver.
 
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loftygoals

loftygoals

Well-Known Member
36*.59=21.24w currently

You're at around 500ppfd at the moment running them at that

If you went to 1.05A you'd have 37.8w each

You'd be at around 880ppfd at that wattage.

640 sqin =0.41 sqm = 4.44 sqft

I may be way off with those calculations, it's past my bedtime :D
 
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Airwalker16

Airwalker16

Well-Known Member
a mongo frog said:
Op don't do that. Do some reserch first. Maybe clean the bottoms up when its time but don't start striping leaves off. Your crop will look like air walkers plants right now. Don't do it. Keep doing what your doing. Your garden looks great!!!
Click to expand...
Like mine look?! You mean fuckin gorgeous?
 
Airwalker16

Airwalker16

Well-Known Member
Bro that defoliation all grew back in about 4 days. And I think @Hybridway will agree that it's something I found very very rewarding and plan on doing from here on out.
 
D

doz

Well-Known Member
Airwalker16 said:
Bro that defoliation all grew back in about 4 days. And I think @Hybridway will agree that it's something I found very very rewarding and plan on doing from here on out.
Click to expand...
Just imagine if the plant didnt have to put all that energy into growing it all back. There is a time for defoliation.... Another thread though.
 
K

kingCharles

New Member
Airwalker16 said:
You should defoliate that shit. And definitely turn up your driver all the way up for flower for sure.
Btw, I like your design. Sweet choice on the 10" sink. But you're only cooling the middle 1/3 of your fins. You oughtta get yourself a 10" case fan for it or switch to 2-140mm ones side by side. You want a fan above any fins that have heat sinking in to them...
That way you'll have no problems cranking out the 50watts each they're capable of hitting with that driver.
Click to expand...
a mongo frog said:
Op don't do that. Do some reserch first. Maybe clean the bottoms up when its time but don't start striping leaves off. Your crop will look like air walkers plants right now. Don't do it. Keep doing what your doing. Your garden looks great!!!
Click to expand...
Thanks I won't be defoliating anything at the moment. I'm still training everything back under the net into open space as they come up.

About the case fan is it's actually off at the moment. The heat sink runs plenty cool on its own, but we'll see if/when I need to turn up the current.


loftygoals said:
36*.59=21.24w currently

You're at around 500ppfd at the moment running them at that

If you went to 1.05A you'd have 37.8w each

You'd be at around 880ppfd at that wattage.

640 sqin =0.41 sqm = 4.44 sqft

I may be way off with those calculations, it's past my bedtime :D
Click to expand...
Thanks for staying on topic. I wasn't familiar with ppfd before this. Did a quick search and am trying to understand what the ideal amount is. Seems like something from 500-700?
 
loftygoals

loftygoals

Well-Known Member
kingCharles said:
Thanks I won't be defoliating anything at the moment. I'm still training everything back under the net into open space as they come up.

About the case fan is it's actually off at the moment. The heat sink runs plenty cool on its own, but we'll see if/when I need to turn up the current.




Thanks for staying on topic. I wasn't familiar with ppfd before this. Did a quick search and am trying to understand what the ideal amount is. Seems like something from 500-700?
Click to expand...
Ideal is debatable.

Google "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions Chandra" and download the PDF. You'll see there is an increase in photosynthesis rates upto 1500ppfd.

However, above 1000 you're probably hitting diminishing returns and putting a lot more energy into lighting for less and less of an increase in yield. There was a nice bar chart someone posted a few days ago which illustrated it well. Maybe someone can dig it up?
 
D

doz

Well-Known Member
800-1200 is optimal. 600-800 will produce good yields still and good product. Above 1200 is nearly a waste of resources. I am currently running my lowest PPFD which is right about 800 before loss. Ive used 1000 and 900 before loss previously and both yielded 1.2g. I am not running all high yield strains though (my last grow yeilded almost 75% more Blue Dream than Kosher Kush for example with 3 plants each in 1000PPFD 4x4 area).

We will see what the yield is this time around. I am running 32sq ft this time (2 4x4) with 9 plants of KK and 3 of BD (compared to 3 and 3 last run) and I am also running 200 less PPFD.
 
Uberknot

Uberknot

Well-Known Member
"How much current do you guys think i should send to these, and at what distance from the canopy?"

I won't give you a bunch of PPFD's or all that....what I will say is I asked someone who has built tons of these and 24" at 1.3 mA was what I was told.for 4xCXB 3590's plain after one week from seedlings. A lot will depend on your set up which is why no one can say exactly what is the perfect distance.

Here are some basic tests results with different set ups I found at 1.41 mA months ago and I think there is a thread here about the whole thing still trying to find it again.

cobresultsa.png cobresultsc.png cobsresults b.png
 
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ReddEyez

ReddEyez

Well-Known Member
loftygoals said:
Ideal is debatable.

Google "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions Chandra" and download the PDF. You'll see there is an increase in photosynthesis rates upto 1500ppfd.

However, above 1000 you're probably hitting diminishing returns and putting a lot more energy into lighting for less and less of an increase in yield. There was a nice bar chart someone posted a few days ago which illustrated it well. Maybe someone can dig it up?
Click to expand...
Here you go. It is on Tasty's website.
 

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K

kingCharles

New Member
doz said:
800-1200 is optimal. 600-800 will produce good yields still and good product. Above 1200 is nearly a waste of resources. I am currently running my lowest PPFD which is right about 800 before loss. Ive used 1000 and 900 before loss previously and both yielded 1.2g.
Click to expand...

Uberknot said:
"How much current do you guys think i should send to these, and at what distance from the canopy?"

I won't give you a bunch of PPFD's or all that....what I will say is I asked someone who has built tons of these and 24" at 1.3 mA was what I was told.for 4xCXB 3590's plain after one week from seedlings. A lot will depend on your set up which is why no one can say exactly what is the perfect distance.

Here are some basic tests results with different set ups I found at 1.41 mA months ago and I think there is a thread here about the whole thing still trying to find it again.

View attachment 3768209 View attachment 3768210 View attachment 3768211
Click to expand...
ReddEyez said:
Here you go. It is on Tasty's website.
Click to expand...
Thanks for all the great info. Previously I did see that thread actually. Helped me choose the KB80's.

I found a calculator by bggrass. Assuming this is accurate, if we want to shoot for 800+ ppfd it says I can turn up the amps to about 1050mA for about 880ppfd. I can try this and lookout for light burn.

Any tips of knowing when too much is too much?
 
loftygoals

loftygoals

Well-Known Member
ReddEyez said:
Here you go. It is on Tasty's website.
Click to expand...
Thanks for posting that.

I've not seen this discussed before; the chart is not "% of maximum photosynthesis" it is "% of maximum photosynthesis per 100ppfd"

That suggests that increasing light upto 1500ppfd does not actually have diminishing returns. It increases photosynthesis for *each 100ppfd* so you somehow have more efficient use of light as well as more total light.

Anyone have any thoughts on this?

Photosynthesis rates may not tally with yield so there's that to consider also.
 
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