Help with par

Chrisz0825

Chrisz0825

Active Member
What par do you guys veg and flower in? I always used a measuring tape to get my lights where they needed to be but recently got a par meter and have been using that to get a more accurate height for the lights. I vegged around 650-700 par and flowering around 1100-1200 par. Because from all the research I've done, those are supposed to be the range you want them in. Well I'm starting to notice some light burn so gotta raise the lights. How much is the question though. I'm running 4 dimmable spider farmer 600w in a 5x5 tent. I saw a guy on YouTube do a par reading and his readings where around 400 to 700. Even a couple in the 200s and those looked as good and dense as the buds with a higher reading. I'm lost here guys. Any help and opinions very much appreciated
 
PetFlora

PetFlora

Well-Known Member
Not sure you understand PAR

Read up on the Farmers Almanac for planting (cooler spectrums) and harvesting (warmer spectrums) according to time of year and color of sun

hth
 
Chrisz0825

Chrisz0825

Active Member
PetFlora said:
Not sure you understand PAR

Read up on the Farmers Almanac for planting (cooler spectrums) and harvesting (warmer spectrums) according to time of year and color of sun

hth
Click to expand...
Always love new info. Will read up on that right now. Thank you
 
nfhiggs

nfhiggs

Well-Known Member
Chrisz0825 said:
What par do you guys veg and flower in? I always used a measuring tape to get my lights where they needed to be but recently got a par meter and have been using that to get a more accurate height for the lights. I vegged around 650-700 par and flowering around 1100-1200 par. Because from all the research I've done, those are supposed to be the range you want them in. Well I'm starting to notice some light burn so gotta raise the lights. How much is the question though. I'm running 4 dimmable spider farmer 600w in a 5x5 tent. I saw a guy on YouTube do a par reading and his readings where around 400 to 700. Even a couple in the 200s and those looked as good and dense as the buds with a higher reading. I'm lost here guys. Any help and opinions very much appreciated
Click to expand...
1100-1200 is on the high side. Above 1000 and the returns diminish quickly. For decent Veg growth 400-700 is good. For flowering I'd go 600-900. Remember temp is critical too - low temps reduce photosynthesis rates. Keep temps above 75 or so during veg, with humidity in the 60's Drop temps and humidity a bit in flower.
 
Chrisz0825

Chrisz0825

Active Member
nfhiggs said:
1100-1200 is on the high side. Above 1000 and the returns diminish quickly. For decent Veg growth 400-700 is good. For flowering I'd go 600-900. Remember temp is critical too - low temps reduce photosynthesis rates. Keep temps above 75 or so during veg, with humidity in the 60's Drop temps and humidity a bit in flower.
Click to expand...
Thank you very much for the info. I will move the lights further away. I'm battling trying to keep humidity up in this cold weather. I have a warm mist humidifier in my veg tent but I can't seem to get humidity in the 60s. I even have my extraction fan on low. Still have beautiful plants in the veg tent just not growing as fast as they should be. I have a cheapo 20 dollar humidifier but I've been looking at a couple on Amazon. Given the price, I'm sure they will work better than the 20 dollar one lol.
 
1

1212ham

Well-Known Member
nfhiggs said:
1100-1200 is on the high side. Above 1000 and the returns diminish quickly. For decent Veg growth 400-700 is good. For flowering I'd go 600-900. Remember temp is critical too - low temps reduce photosynthesis rates. Keep temps above 75 or so during veg, with humidity in the 60's Drop temps and humidity a bit in flower.
Click to expand...
I still need to research light measurements and units etc..... Can lux measurements at the top of the canopy be used directly or is it necessary to convert to par etc.? In another thread I mentioned that I had 27,000 lux at the canopy (veg) and some one said I should have 40,000. I then cranked up the lights to 40,000 and looked at my power draw, it was pushing something like 45 watts/ft. for veg! Edit: I think it was more like 35 w/ft.
Lights are 175Lm/watt, EB series Gen-2.
 
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nfhiggs

nfhiggs

Well-Known Member
1212ham said:
I still need to research light measurements and units etc..... Can lux measurements at the top of the canopy be used directly or is it necessary to convert to par etc.? In another thread I mentioned that I had 27,000 lux at the canopy (veg) and some one said I should have 40,000. I then cranked up the lights to 40,000 and looked at my power draw, it was pushing something like 45 watts/ft. for veg!
Lights are 175Lm/watt, EB series Gen-2.
Click to expand...
If your LEDs are white, you can approximate PPFD from the LUX measurement to within about 10% for most common spectrums - divide the lux value by 70. How far were the lights from the canopy?
 
nfhiggs

nfhiggs

Well-Known Member
1212ham said:
I think that was 16-18"?. Right now it's 13" and still 27,000 lux, 21 watts/ft.
3500K.
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You can move them much closer for higher light levels at the canopy. I would get the power up to at least 30W per square foot, then move them to where the top of the canopy is getting at least 40k lumens. Increase it gradually so you don't shock them.
 
wietefras

wietefras

Well-Known Member
Chrisz0825 said:
Thank you very much for the info. I will move the lights further away. I'm battling trying to keep humidity up in this cold weather. I have a warm mist humidifier in my veg tent but I can't seem to get humidity in the 60s. I even have my extraction fan on low. Still have beautiful plants in the veg tent just not growing as fast as they should be. I have a cheapo 20 dollar humidifier but I've been looking at a couple on Amazon. Given the price, I'm sure they will work better than the 20 dollar one lol.
Click to expand...
Since you can dim the fixture, why not use dimming to reduce the light intensity? Moving it higher wastes light (and electricity) on the walls.

The height of the fixture should normally be adjust to get the right uniformity and then the intensity is adjusted by dimming.
 
K

kushedy

Well-Known Member
Interesting. I've got 1 cob psf which I have been running at 40w per cob in flower. Just used a lux meter app & converted the lux reading to par & it came out at around 1400 par! doh
Plants seem happy enough bar a little yellowing at the tips which I put down to me possibly running to high an EC level.
Is it possible that using too much light somehow forces plants to gorge on feed in order to keep up with all the extra light & subsequently causes over feeding?
 
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