Lighting vs yield

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dba1954

Well-Known Member
I have a question about yield and lighting. This is for indoor grow, no CO2, LED only....

I've read that
-- 30-50 watt per sqft is ideal (true ?)
-- the higher the PPFD the higher the yield to what level?
-- > 1000 ppdf will burn plants (true?)
-- many lights have 1200- 2000 ppfd, is that just for coverage? it seems clearly exceeds 1000 ppfd
-- i grow in a 3x3x6ft tent, what would be the ideal wattage for a small space such as that?

Comments?
 
dba1954 said:
I have a question about yield and lighting. This is for indoor grow, no CO2, LED only....

I've read that
-- 30-50 watt per sqft is ideal (true ?)
-- the higher the PPFD the higher the yield to what level?
Click to expand...

definitely. level depends on other factors, including but not limited to exposure hours, rh, temp, and air circulation.





dba1954 said:
-- > 1000 ppdf will burn plants (true?)
Click to expand...


not really. it depends on other factors not just ppfd.


dba1954 said:
-- many lights have 1200- 2000 ppfd, is that just for coverage? it seems clearly exceeds 1000 ppfd
-- i grow in a 3x3x6ft tent, what would be the ideal wattage for a small space such as that?
Click to expand...

depends on the light. budget for 35w sq/ft minimum. a lower quality light will need more watt to hit the same ppfd.

light will always be your number one factor, but it can't work without the support of the others.
 
In a 3x3 300-350w LED would be ideal or 400w HID. I would aim for somewhere between 250-300 LED since it will be easier to grow healthy plants with lower ceiling using less wattage.
 
Phytoplankton said:
I believe the sweet spot for LED's is between 30-40 watts/sqft. Less than 30 your yield will suffer, more than 40 and you can get burn issues (plus youre just wasting electricity).
Click to expand...


a pile depends on the diodes/emitters. most modern white light led rigs will be to the lower end of the 35-50w scale. lesser rigs will run higher, 35 - 40w should be sufficient for most rigs.

there are some budget lights i would stay away from, and i would never recommend a non white light rig.

drivers also need to be taken in to account. the efficacy of the whole rig is intrinsically tied to both. they can't be separated.
 
dba1954 said:
i have 2 Mars Hydo ts1000 lights in a 3x3 tent, I can easily get over 1000 ppfd. I was wondering how high should I go but was wondering about in general terms. I could put a 450 watt in there but if I cant use it, whats the purpose.
Click to expand...
Don't trust any app on your phone. Even if you can measure that(1000ppfd) it doesn't mean the light distance is even usable.

150w is not sufficient in a 3x3.
 
I use LED quantum boards 2700k - 3500k. I have three fixtures in a 3' x 5.5' space, for a total of around 780 watts if they are all turned up all of the way. They are dimmable. I keep them dimmed during veg and turn them up slowly during flower. Distance from plants is also a factor.
 
bluter said:
a pile depends on the diodes/emitters. most modern white light led rigs will be to the lower end of the 35-50w scale. lesser rigs will run higher, 35 - 40w should be sufficient for most rigs.

there are some budget lights i would stay away from, and i would never recommend a non white light rig.

drivers also need to be taken in to account. the efficacy of the whole rig is intrinsically tied to both. they can't be separated.
Click to expand...
I'm basing it on a quality rig with Samsung 301B or 301H chips, osram red, with a brand name driver. 100% agreement, budget Amazon/Alibaba lights are "like a box of chcolates, you never know what you're going to get".
 
Large lights are great for larger area footprint. Are you familiar with the inverse square law of light? Light = the inverse of the distance squared. L / D squared. Measured one foot from the source, landing on one square foot surface = 1000ppfd. At 2 foot from source Light is 1000 (Distance) 2 squared. So 1000ppfd /4 = 250ppfd per square foot but covering 4 square foot.
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The closer you get to optimum light levels the more your returns diminish. For example if your grow optimum was 1000ppfd and minimum to grow was 500ppfd. 500 increased to 600 would be a vary noticeable, obvious, yield and quality increase. Increasing from 900 to 1000 you won't notice the increase without an accurate scale comparison. This bell curve of optimizing applies to almost all aspects of growing plants. Every strain and grow rooms optimum is going to vary.
 
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