Is this enough LED for now?

aquanaut

Well-Known Member
Makes total sense to me now! :)

Ok, so seeing as I don't have a PAR meter of sorts.. what distance do people normally keep their cobs at? For reference my tent is only 4' wide by 2' deep. I'll have six leds running horizontally down the 4' run. 2 heat sinks, 3 cobs per. Pretty much a line of 3590s.
 

kushedy

Well-Known Member
@aquanaut I am growing in identical dimensions with 8 x cxb3590. I asked this question on another forum a while ago. The response I got back from a well known member was:
@1400mA - 25-35cm
@700mA - 20cm

I'm only on my 2nd grow now with these lights. On my first grow I did, I ran the cobs at 1050ma (37w per cob) & kept a distance of 30cm from canopy. I ended up with one bud with a little light bleaching on the tip. The rest were ok. I'm presently running at 31w per cob at a distance of about 40cm from canopy. So far so good but I'm only a week into flower so its early days.
Would be nice if any of the more experienced LED users could give a range of hanging distances all the way from 350ma up to ............what ever the max amperage is people are using these days.
 

Randomblame

Well-Known Member
@350mA with CXB2540 I see no sign of stress also at 4"
@700mA ~8" should be okay
@1050mA ~12"
@1400mA ~18"
@2100mA ~24"

But it also depends on total wattage/ppfd. With 600w of LED/~2000ppfd in a 4' x 2' you will get bleaching also if you ran the COB's at 350-700mA and 18"

<1000μMol/s is relatively safe to use,
>1000 is critical,
>1500 cause bleaching without CO² even at 18"

I'm using a cheap 10$ lux-meter and conversion factors to get an idea of my ppfd.
For instance, 8 CXB3590@1050mA, 1m², at 18" gives me 50.000lx measured at canopy level x 0,014152(conversions factor for 3.500k/CXB) =~700-710μMol/s = no bleaching.
But with the same setup at 12" (60.000lx) =~850μMol/s i get sign of bleaching.
You must try to find the sweetspot by watching your babies well! Lower currents are allways helpful but not the only reason for bleaching.
Not to mention that different strains also have different requirements. An equatorial sativa is most probably more tolerant than a dutch outdoor cultivation like HollandsHope!
 
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