LED hanging height in too big a tent.

Narsbars · Oct 25, 2021

I have two photo periods growing, I vegged for six weeks and then went 12/12. The situation is this, I am growing in 5 gal. buckets using a soil mix of FF Ocean Forest and perlite, a 4x4 tent about seven foot tall, and two Viparspectra P1500s. I know the problems with this setup but I have to work with what I have and can afford. I have been using a 15 inch from the top hanging height, topping, training, and defoliation on both plants. They are both about 17 inches tall two weeks into flowering on an 11 on 13 off lighting schedule with only tiny buds starting as I defoliated about one week into flowering.
How high would you hang the lights during the rest of flowering seeing as it is in an oversize tent that could support 4 of these lights?

MilkyTrichomes · Oct 25, 2021

I use the Photone app on my Iphone and dial in the PPFD/DLI. Depending on your grow set up and conditions the numbers might be different so I hesitate to throw out numbers. My plants do well at around 600 PPFD/ 42 DLI in veg. My lights( 2x HGL 260xl) are @18” and 50% pwr., seems to be a sweet spot. In a few weeks I’ll be giving them more power but less time on (12 vs 18hrs) when I flip to flower. I suspect I’ll kick it up 10% pwr and lower my lights weekly while monitoring my DLI. Good luck, hope this helps.

Narsbars · Oct 25, 2021

MilkyTrichomes said:
I use the Photone app on my Iphone and dial in the PPFD/DLI. Depending on your grow set up and conditions the numbers might be different so I hesitate to throw out numbers. My plants do well at around 600 PPFD/ 42 DLI in veg. My lights( 2x HGL 260xl) are @18” and 50% pwr., seems to be a sweet spot. In a few weeks I’ll be giving them more power but less time on (12 vs 18hrs) when I flip to flower. I suspect I’ll kick it up 10% pwr and lower my lights weekly while monitoring my DLI. Good luck, hope this helps.

Just grabbed the Photone app. Comparing it to the manufacturer, or to PAR map provided on Cocoforcannabis it is showing about 1/3 to 1/2 of the expected PAR. I will have to see if there are other settings that can make it more accurate. Thanks for the lead.

PipeCarver · Oct 25, 2021

Narsbars said:
I have two photo periods growing, I vegged for six weeks and then went 12/12. The situation is this, I am growing in 5 gal. buckets using a soil mix of FF Ocean Forest and perlite, a 4x4 tent about seven foot tall, and two Viparspectra P1500s. I know the problems with this setup but I have to work with what I have and can afford. I have been using a 15 inch from the top hanging height, topping, training, and defoliation on both plants. They are both about 17 inches tall two weeks into flowering on an 11 on 13 off lighting schedule with only tiny buds starting as I defoliated about one week into flowering.
How high would you hang the lights during the rest of flowering seeing as it is in an oversize tent that could support 4 of these lights?

Hi, I hit stop when I saw the 11 on 13 off cycle.....Bin there done that.....I won't do it again.....smaller airier, lighter lower thc & taste was meh.....I'm back to 12/12 Who ever got you onto that is off target....unless a lower quality product is what you are looking for... GL what ever you do.

I have a cheap lux meter I'm using to judge the height I keep my light...I'm new to led's but right now I have my light at 17" with a lux of 20,000....I just turned it to 12/12 my plant is growing into the light so I'm hoping it will increase in lux up until Its within 10" of the plant near the end and I'll just have to watch for the plant complaining. I'll tie her down more if she stretches too much

DankNugz420 · Oct 25, 2021

So far from my experience using viparspectra p1000s my plants seem happiest at 18 to 20 inches from canopy. Still haven't been able to throw 100% power at them yet at that distance but am close at about 80% power. P1500 are a bit more robust so you'll have to experiment and see what distance and power your plants are happy with but I think 18 to 20 is a good area to try
Edit: I just looked and my lights are actually at 90% power the last few days

Narsbars · Oct 25, 2021

PipeCarver said:
Hi, I hit stop when I saw the 11 on 13 off cycle.....Bin there done that.....I won't do it again.....smaller airier, lighter lower thc & taste was meh.....I'm back to 12/12 Who ever got you onto that is off target....unless a lower quality product is what you are looking for... GL what ever you do.

I have a cheap lux meter I'm using to judge the height I keep my light...I'm new to led's but right now I have my light at 17" with a lux of 20,000....I just turned it to 12/12 my plant is growing into the light so I'm hoping it will increase in lux up until Its within 10" of the plant near the end and I'll just have to watch for the plant complaining. I'll tie her down more if she stretches too much

I was concerned about the 11/13. That is one variable I think I will change back. It does add total photons. Thanks

Narsbars · Oct 25, 2021

DankNugz420 said:
So far from my experience using viparspectra p1000s my plants seem happiest at 18 to 20 inches from canopy. Still haven't been able to throw 100% power at them yet at that distance but am close at about 80% power. P1500 are a bit more robust so you'll have to experiment and see what distance and power your plants are happy with but I think 18 to 20 is a good area to try

I have grown autoflowers with the P1500s and I "accidentally" set them at 12 on 12 off due to the AFs coming up during Flowering of some photos. Made some great smoke. The hardest thing is you can get a PAR map for one light but no one has tested two side by side. I am leaning on going to 20 to 22 inches and as a commenter suggested returning to a 12/12 instead of an 11/13.

growsince79 · Oct 25, 2021

Narsbars said:
Just grabbed the Photone app. Comparing it to the manufacturer, or to PAR map provided on Cocoforcannabis it is showing about 1/3 to 1/2 of the expected PAR. I will have to see if there are other settings that can make it more accurate. Thanks for the lead.

Don't compare to manufacturers map. They lie.

Narsbars · Oct 26, 2021

growsince79 said:
Don't compare to manufacturers map. They lie.

There is a site I go to that has comprehensive testing on many grow lights. I use their results as far as possible but if they have tested in a 2x4 you have to adjust the numbers down going to a 4x4 because you are farther from at least two of the walls. In this case the test results are not far off the manufacturer reports.

frogyrogy · Oct 26, 2021

MilkyTrichomes said:
I use the Photone app on my Iphone

Have you compared your results with any other meter? I used an iPhone (w/diffuser) and got light adjusted to a reasonably even 750-800 ppfd, checked it with an Andriod phone using same app and couldn't get a reading higher than 200-300 anywhere, that's when I learned that you need to calibrate the app using a "trusted" meter or a pre-calibrated phone prior to use. I tried the app under an HLG Scorpion rspec, the Andriod phone reads 300-350 at 2" below one of the boards. Neither phone is the most recent version, and the Android lived in the work/rock hunting truck for a couple years so I'm not saying I used test quality phones, but until I can buy/borrow a real meter I'll just dial the lights up up or down based on those green meters that live there.

Narsbars · Oct 26, 2021

frogyrogy said:
Have you compared your results with any other meter? I used an iPhone (w/diffuser) and got light adjusted to a reasonably even 750-800 ppfd, checked it with an Andriod phone using same app and couldn't get a reading higher than 200-300 anywhere, that's when I learned that you need to calibrate the app using a "trusted" meter or a pre-calibrated phone prior to use. I tried the app under an HLG Scorpion rspec, the Andriod phone reads 300-350 at 2" below one of the boards. Neither phone is the most recent version, and the Android lived in the work/rock hunting truck for a couple years so I'm not saying I used test quality phones, but until I can buy/borrow a real meter I'll just dial the lights up up or down based on those green meters that live there.

The trouble is that I can't compare it to a meter, but getting the same results you did on my Pixel 3. I will set up a light at the same distance used by Cocoforcannabis measure at the same spot and use that number to calibrate. Probably not great but the best I can do. Take a look at Photometer Pro. The directions can be murky but a good app.

CannaDana · Oct 26, 2021

I'm a newbie, not an old hand, but I've been studying like crazy. So take my advice for what it's worth, which isn't much. Others may know much more than me.

I use Photone. It's just not good enough to be trusted. It gives a very general idea, but isn't reliable enough to use in fine tuning, IMHO, especially if you don't have a meter to calibrate it.

Yeah, you gotta get that photoperiod back to 12/12. If you were running 900+ ppfd, maybe you could get away with 11/13, but you need the daily photons to be up there, and with your lights and on your schedule you're just not getting it. But just 2 weeks into flower, you're not going to be seeing much flowering yet, anyway, mostly stretch and pre-flower.

I haven't used your lights, but the PAR map provided by the manufacturer shows a huge drop-off from center to edge, not uncommon for quantum board lights. You should probably have them hung several inches to a foot apart so you get more even coverage. Doing that, I'd probably hang them at whatever height gives the most even coverage, trying to keep it less than 900 ppfd in the middle and above 600 near the edges. Might take some experimenting. You could hang them lower to get more light in the center of your canopy, but then you'll experience a huge drop-off near the edges. The problem I'd have with this setup is that your lights aren't strong enough that you can hang them a good distance up for even coverage and still get enough ppfd for a good flower yield. I'd frankly invest in a better bar light.

I have basically your same setup with different lights. I opted for a stronger bar-style LED light, for more even coverage. I bought the Grower's Choice ROI-E720, which is a commercial quality light. Yes, it cost me a bunch more money than you spent. But I can hang it high and have very even coverage over the canopy while still maintaining around 900 ppfd in the center and 790 ppfd on the edges. With a 4X4 space and one bar light, with FF Ocean Forest and perlite, in 5 gal bags. I vegged for four weeks and then flowered. I'm in Week 7 of flower now, and the colas are getting big and fat. I'm told I'm going to yield 1.5-2 lbs from this grow (we'll see!), largely due to the light I'm using. IMHO, if you're going to spend money on one thing, it should be the very best quality LED light you can afford. Yours are fine for veg, but you really need more for flower, IMHO. And personally, I prefer bar lights for more even coverage.

Narsbars · Oct 26, 2021

CannaDana said:
I'm a newbie, not an old hand, but I've been studying like crazy. So take my advice for what it's worth, which isn't much. Others may know much more than me.

I use Photone. It's just not good enough to be trusted. It gives a very general idea, but isn't reliable enough to use in fine tuning, IMHO, especially if you don't have a meter to calibrate it.

Yeah, you gotta get that photoperiod back to 12/12. If you were running 900+ ppfd, maybe you could get away with 11/13, but you need the daily photons to be up there, and with your lights and on your schedule you're just not getting it. But just 2 weeks into flower, you're not going to be seeing much flowering yet, anyway, mostly stretch and pre-flower.

I haven't used your lights, but the PAR map provided by the manufacturer shows a huge drop-off from center to edge, not uncommon for quantum board lights. You should probably have them hung several inches to a foot apart so you get more even coverage. Doing that, I'd probably hang them at whatever height gives the most even coverage, trying to keep it less than 900 ppfd in the middle and above 600 near the edges. Might take some experimenting. You could hang them lower to get more light in the center of your canopy, but then you'll experience a huge drop-off near the edges. The problem I'd have with this setup is that your lights aren't strong enough that you can hang them a good distance up for even coverage and still get enough ppfd for a good flower yield. I'd frankly invest in a better bar light.

I have basically your same setup with different lights. I opted for a stronger bar-style LED light, for more even coverage. I bought the Grower's Choice ROI-E720, which is a commercial quality light. Yes, it cost me a bunch more money than you spent. But I can hang it high and have very even coverage over the canopy while still maintaining around 900 ppfd in the center and 790 ppfd on the edges. With a 4X4 space and one bar light, with FF Ocean Forest and perlite, in 5 gal bags. I vegged for four weeks and then flowered. I'm in Week 7 of flower now, and the colas are getting big and fat. I'm told I'm going to yield 1.5-2 lbs from this grow (we'll see!), largely due to the light I'm using. IMHO, if you're going to spend money on one thing, it should be the very best quality LED light you can afford. Yours are fine for veg, but you really need more for flower, IMHO. And personally, I prefer bar lights for more even coverage.

I have been working with Photone and have gotten it close to a trusted PAR map done by Cocoforcannabis.com I have already returned to the 12/12 and they only had to deal with that for two days. You are correct, both the map and personal testing shows a drop off. I have two plants at about 15 to 19 inches tall, both defoliated on the inner branches and they seem to have recovered from that just fine. Using Photone, comparing to the known PAR at 14 inches I would estimate hanging the lights at 15 inches from the crown I am hitting a minimum of 775, probably more as each light spreads a little to cover the other footprint at least in the center. It appears to drop off to 500 PPFD for most of the footprint which is my understanding of minimum PPFD for any success. I left one plant only topped once and defoliated once. The other has been defoliated and trained at all branches to grow Horizontal for several inches and has put up a truly surprising number of bud sites. I continue the training with the intent to have all Colas level to see if that helps with the lighting. I have to work with what I have and would love a brighter light but will have to make do.

PipeCarver · Oct 26, 2021

CannaDana said:
I'm a newbie, not an old hand, but I've been studying like crazy. So take my advice for what it's worth, which isn't much. Others may know much more than me.

I use Photone. It's just not good enough to be trusted. It gives a very general idea, but isn't reliable enough to use in fine tuning, IMHO, especially if you don't have a meter to calibrate it.

Yeah, you gotta get that photoperiod back to 12/12. If you were running 900+ ppfd, maybe you could get away with 11/13, but you need the daily photons to be up there, and with your lights and on your schedule you're just not getting it. But just 2 weeks into flower, you're not going to be seeing much flowering yet, anyway, mostly stretch and pre-flower.

I haven't used your lights, but the PAR map provided by the manufacturer shows a huge drop-off from center to edge, not uncommon for quantum board lights. You should probably have them hung several inches to a foot apart so you get more even coverage. Doing that, I'd probably hang them at whatever height gives the most even coverage, trying to keep it less than 900 ppfd in the middle and above 600 near the edges. Might take some experimenting. You could hang them lower to get more light in the center of your canopy, but then you'll experience a huge drop-off near the edges. The problem I'd have with this setup is that your lights aren't strong enough that you can hang them a good distance up for even coverage and still get enough ppfd for a good flower yield. I'd frankly invest in a better bar light.

I have basically your same setup with different lights. I opted for a stronger bar-style LED light, for more even coverage. I bought the Grower's Choice ROI-E720, which is a commercial quality light. Yes, it cost me a bunch more money than you spent. But I can hang it high and have very even coverage over the canopy while still maintaining around 900 ppfd in the center and 790 ppfd on the edges. With a 4X4 space and one bar light, with FF Ocean Forest and perlite, in 5 gal bags. I vegged for four weeks and then flowered. I'm in Week 7 of flower now, and the colas are getting big and fat. I'm told I'm going to yield 1.5-2 lbs from this grow (we'll see!), largely due to the light I'm using. IMHO, if you're going to spend money on one thing, it should be the very best quality LED light you can afford. Yours are fine for veg, but you really need more for flower, IMHO. And personally, I prefer bar lights for more even coverage.

At what cost do you invest in led lights? I just did a quick search on your light $850.Usa + shipping. = about $1500 Cdn I'm guessing..That's a whack of cash for a light. How long will it last? running veg through flower? 3 yrs? I'm just guessing with the quality of building any electric / electronic equipment these days.....I know bigger and badder is better but tough on a budget...We can buy, delivered by the oz for around $100cdn around here. it all comes down to what you can afford I guess. But I can't afford me no $1500 lights....not and stay married.

Narsbars · Oct 26, 2021

PipeCarver said:
At what cost do you invest in led lights? I just did a quick search on your light $850.Usa + shipping. = about $1500 Cdn I'm guessing..That's a whack of cash for a light. How long will it last? running veg through flower? 3 yrs? I'm just guessing with the quality of building any electric / electronic equipment these days.....I know bigger and badder is better but tough on a budget...We can buy, delivered by the oz for around $100cdn around here. it all comes down to what you can afford I guess. But I can't afford me no $1500 lights....not and stay married.

The Viparspectra P1500 is currently about $100.00 US. I may have paid $115.00.

PipeCarver · Oct 26, 2021

Narsbars said:
The Viparspectra P1500 is currently about $100.00 US. I may have paid $115.00.

That is more inline withe sf1000 +50w I have, it's ample for veg I just turned a Bubble Bomb under it I'll see how it goes....I'm expecting a larger light this week ( Se3000 from Spider Farmer. ) and I'll finish this BB under it. My first grow with led lights. I'm used to t5's and a 1000w hps to flower under. This BB is a clone from a mother 6+weeks in flower. I cut this clone the same day I flipped to 12/12.

Narsbars · Oct 26, 2021

This is one at a total of 9 weeks from putting the seed in a paper towel. This is the one grow to have multi tops. I have two main branches at the top. So far I have about 20 colas at least on the same level. Hoping to share the light this way.

Narsbars · Nov 1, 2021

Update: Anyone have a guess on the effects of using only two Viparspectra P1500s in a 4x4? My thought process is that since I am only growing two plants the extra reflective surface available may compensate for having less light. They were put into 12/12 after a six week veg, on October 5, today is Nov. 1. So far I have a lot of preflowers but nothing that could be called a real bud. Will add a picture.

lvstealth · Nov 1, 2021

Aquaman recommended this app

Lux Meter (Light Meter) - Apps on Google Play

Professional light intensity (lux) meter for your android device.

play.google.com

for flower i aim for 60k. then i dial it in by watching the plants and adjusting. i run mine too high, but it is right on the line of what they can take. i need co2, but i dont have it.

as far as using 2 lights in a tent that would hold 4, i think you overcome the question using the meter. but... lol, i would 1/4 turn plants every watering. my theory (i built up to all the lights) when i was doing it was that the side not in the "reflective zone" would always rotate around. but honest, i saw no real difference. and learned a lot in driving the plant.

lvstealth · Nov 1, 2021

oh! and for me, toward the end, i need to dim my lights a little each few days.

but i run mine so that they hit "fall" so the leaves start turning and with fewer leaves they get too much light which makes too much heat.

i have an old phone i leave in the tent so i can check the lux and all remotely and adjust almost instantly. i just use the phone's sensor and alexa or google. but i love the feedback and all the numbers! lol

LED hanging height in too big a tent.

LED hanging height in too big a tent.

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