How much light is “too much”??

kacikoby · Jul 20, 2019

Ok we have a 4x4x8 tent and a 2x4x6.5 tent, and a bunch of lights. we had a few of them in our 4x4 with the plants but some have shown heat damage so now we’re looking for suggestions on where to put what. hoping for some input!! this is the options:
630w CMH
600w full spectrum LED w/veg & bloom switches (2 of these)
600w full spectrum LED - no switches
1200w full spectrum LED w/ switches
1200w full spectrum LED w/ 2 COBs and switches for veg/bloom

Right now, our 4x4 has just the 630 CMH and our 4 flowering plants. we had the 2 600w and the regular 1200w in there as well but they’re showing signs of stress. Someone suggested to decrease the lights and get rid of the LEDs for now.

So our question is, what lights should go where? We have the COB light in our 2x4 with some clones ready to be flipped. so essentially wondering where to put the lights for our next grow. we would like to take the 4 clones and flip them in the 4x4 when the flowering plants are done (which is soon) so what lights would be best for this given our current options?
thanks!!

BigCube · Jul 20, 2019

I have a 3x3 with a 1500w cob led in it. Actual draw is 250w . It's almost too much for the tent.

az2000 · Jul 20, 2019

I like to think of light in terms of watts per square foot. CMH is about 35w/sq ft. A 315 LEC works well in a 3x3 tent. In a 4x4, you have to add 200-250 watts around the perimeter using four single-tube T5HO, or LED lightbulbs.

Your 630w CMH doesn't fit either tent very well. It's probably a rectangle coverage, but too much for your 2x4 tent.

What are the actual watts of the LED fixtures? LED is a mixed bag (IMO). Decent fixtures can run 25-30w/sq ft. (Very good ones can do 20w/sq ft). The average Amazon light should probably cover 40w/sq ft.

I think about my grow spaces that way.

Munch517 · Aug 5, 2019

That seems like a lot of light for that space, especially if you don't have Co2. In a perfect world you would have a par meter and you could definitively know how many lights to have and where to place them. Without Co2 you'd go for no more than 500-600 ppfd in veg and no more than 900-1000 in flower, possibly less. A decent PAR meter costs almost $400 (the cheaper Apogee), instead you could get a $20-$30 Amazon lux meter that will work fine with your hid light and I've been told it's fairly accurate for the white light LEDs. I go for 30k-50k lux in veg and 70k lux at the center in flower, I've found too much more and buds start to bleach on my plants.

Use the lights that let you get the most even light at the intensity you want over your whole canopy. That cmh is probably as effecient or more efficient than those LEDs for whatever that's worth.

az2000 · Aug 5, 2019

Munch517 said:
A decent PAR meter costs almost $400 (the cheaper Apogee), instead you could get a $20-$30 Amazon lux meter that will work fine with your hid light and I've been told it's fairly accurate for the white light LEDs. I go for 30k-50k lux in veg and 70k lux at the center in flower, I've found too much more and buds start to bleach on my plants.

I have a Sunche HS1010 lux meter ($17 USD on Amazon). I recently bought an Apogee MQ-500 PAR meter. If someone bought the Sunche, I could do some comparisons of cool and warm light to have a conversion factor.

The PAR meter uses clearskycalculator.com to verify the meter is calibrated. That could be a way to convert a lux meter's reading to PAR. (Enter your lat/long, altitude, time of day, day of year.).

Munch517 · Aug 7, 2019

az2000 said:
I have a Sunche HS1010 lux meter ($17 USD on Amazon). I recently bought an Apogee MQ-500 PAR meter. If someone bought the Sunche, I could do some comparisons of cool and warm light to have a conversion factor.

The PAR meter uses clearskycalculator.com to verify the meter is calibrated. That could be a way to convert a lux meter's reading to PAR. (Enter your lat/long, altitude, time of day, day of year.).

I have the Dr Meter one but if you get around to making comparisons I'd be interested in seeing them anyways. I can't imagine lux meters are that different from each other

az2000 · Aug 7, 2019

Munch517 said:
I have the Dr Meter one but if you get around to making comparisons I'd be interested in seeing them anyways. I can't imagine lux meters are that different from each other

FWIW: I just measured a new warm-white LED lightbulb. Using the Apogee MQ-500: 485 ppfd. Using the Sunche HS1010 meter: 24,000 lux.

You mentioned 30-50k veg, 70k flower. I think 30k sounds good for veg. But, for flower, if these numbers track each other, 70k would be high ppfd. I've read 900 ppfd is the point of diminishing returns. 45,000 would be about that (if the numbers scale together that way).

I haven't had the PAR meter long. I should measure the sun using that clearsky site. I could use the lux meter too.

Munch517 · Aug 7, 2019

az2000 said:
FWIW: I just measured a new warm-white LED lightbulb. Using the Apogee MQ-500: 485 ppfd. Using the Sunche HS1010 meter: 24,000 lux.

You mentioned 30-50k veg, 70k flower. I think 30k sounds good for veg. But, for flower, if these numbers track each other, 70k would be high ppfd. I've read 900 ppfd is the point of diminishing returns. 45,000 would be about that (if the numbers scale together that way).

I haven't had the PAR meter long. I should measure the sun using that clearsky site. I could use the lux meter too.

Thanks, the 485 ppfd to 24k lux for warm white light is a useful baseline for me. I agree that if the numbers do scale like that 70k lux is probably really pushing it, but I've noticed significantly better bud growth in the spots with 60k+ lux compared with the spots at or below 50k lux on my Spydr 2p. I really need to just fork over the money for a PAR meter

az2000 · Aug 7, 2019

Munch517 said:
Thanks, the 485 ppfd to 24k lux for warm white light is a useful baseline for me. I agree that if the numbers do scale like that 70k lux is probably really pushing it, but I've noticed significantly better bud growth in the spots with 60k+ lux compared with the spots at or below 50k lux on my Spydr 2p. I really need to just fork over the money for a PAR meter

I took three more measurements:

The sun measurement isn't reliable. High/thin clouds caused it to move from 1100 to 1600ppfd. I tried to look at both meters simultaneously. But, they could process at different speeds. I'll measure it again someday when it's perfectly clear.

The Cree 95 CRI lightbulb might produce more ppfd (per lux). The other two 2700k readings were an old Philips (probably the typical 80+ CRI).

Aqua Man · Aug 7, 2019

Munch517 said:
That seems like a lot of light for that space, especially if you don't have Co2. In a perfect world you would have a par meter and you could definitively know how many lights to have and where to place them. Without Co2 you'd go for no more than 500-600 ppfd in veg and no more than 900-1000 in flower, possibly less. A decent PAR meter costs almost $400 (the cheaper Apogee), instead you could get a $20-$30 Amazon lux meter that will work fine with your hid light and I've been told it's fairly accurate for the white light LEDs. I go for 30k-50k lux in veg and 70k lux at the center in flower, I've found too much more and buds start to bleach on my plants.

Use the lights that let you get the most even light at the intensity you want over your whole canopy. That cmh is probably as effecient or more efficient than those LEDs for whatever that's worth.

Exactly this... Numbers are exactly as I find too. I can push about 80,000 with CO2 but it's right at that edge where I would not go more.

How much light is “too much”??

How much light is “too much”??

kacikoby

BigCube

az2000

Munch517

az2000

Munch517

az2000

Munch517

az2000

Aqua Man

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