Randomblame
Well-Known Member
That's the lux readings I have in my germination area.
Height/Power to canopy for Samsung Led’s
- Thread starter SMT69
- Start date
Retardid_greenthumb
Active Member
Plant size?Can someone tell me where to begin to figure out how high to hang the lights and at what power.
I’ve just been guessing and experimenting and that’s probably not a good thing for a first gro
I’ve been going by the general 30w a sq ft and hang up between 12”-18”
Running samsung 561c strips
Area is 8 sq ft (2x4 tent)
Thoughts?
SMT69
Well-Known Member
Thx RB ,
I’ve got that same lux probe on order.
With the approximately 10% -/+ accuracy drop on these, what lux should i shoot for in Bloom...still 40,000-50,000? 800 ppfd ? Really want to run these F strips as close as possible.
funny thing is evey LED grow with big buds. that I’m seeing on here, everyone’s got them from 12-18” and some guys are 20-30”.
I’ve yet to see any journal with someone running newer leds/qb’s up close and dimmed. Seems most are up high and cranked.
Take a look at this...I was browsing some LED grows and have been intrigued by the way he hangs his so low
Nice buds, not fat and solid looking, could be genetics I suppose
Anyone running like this?
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canadian1969
Well-Known Member
This is an interesting conversation, I love the SGS video btw. I constantly link to it in posts.
I made some adjustments and took some more careful readings today, just to really get my head around the losses in a small tent. I had to make some adjustments to the maximum height of my panel so my previous numbers are invalid.
First I turned off half the strips in my build, leaving just the 3000K on. (I have double the number of strips for colour temp experimentation - 8x5700K, 8x3000K), so just with the 3000K on and the diodes at roughly 2.5" centers. Turned the power to 100 watts, for the sake of easy math. The panel itself is 24" square. The tent is 27"x27".
From the emitters to the floor of the tent = 51"
I took readings until I found uniformity, which was 16" below the panel and 22K LUX
From there I took readings down to the canopy, which is basically the floor in this case, just cups with seedlings, normally the canopy (after putting in the bottom grill, grow bags and scrog screen) would be 24" from the floor (27" from the panel)
So right away I know that 16' to 18" is the best height in the test as uniformity is essential.
I then took readings starting at 16" down to 46" (tops of plants)
Chart
https://imgur.com/a/rwGKPTX
That little hiccup just happens to be were the clip on fan is attached in a corner at roughly 23".
Now lets say I want to be at 16500 LUX @ 16"; (At a guess this is probably 300 PPFD or early veg, seems to be what the plants like, still in cups and only 2 nodes) to achieve this I had to reduce the power to 75 watts. Saving 25% electricity at the point of general uniformity. Take 16500/22000=0.75 bingo , pretty damn linear. Assuming I have done the calculations correctly as I suck at math
.
props to @wietefras
A comparable chart that conforms to the Inverse square law would look like this.
https://imgur.com/a/jPwwynq
I think we can conclude that over distance you lose as much but you dont get that initial sag in a tent as seen in the second chart. I also bet that the larger the tent the more likely the losses would conform to the inverse square law, as would having point source i.e. 100 watt COB in this example, instead of a strip or QB type "panel of light".
I made some adjustments and took some more careful readings today, just to really get my head around the losses in a small tent. I had to make some adjustments to the maximum height of my panel so my previous numbers are invalid.
First I turned off half the strips in my build, leaving just the 3000K on. (I have double the number of strips for colour temp experimentation - 8x5700K, 8x3000K), so just with the 3000K on and the diodes at roughly 2.5" centers. Turned the power to 100 watts, for the sake of easy math. The panel itself is 24" square. The tent is 27"x27".
From the emitters to the floor of the tent = 51"
I took readings until I found uniformity, which was 16" below the panel and 22K LUX
From there I took readings down to the canopy, which is basically the floor in this case, just cups with seedlings, normally the canopy (after putting in the bottom grill, grow bags and scrog screen) would be 24" from the floor (27" from the panel)
So right away I know that 16' to 18" is the best height in the test as uniformity is essential.
I then took readings starting at 16" down to 46" (tops of plants)
Chart
https://imgur.com/a/rwGKPTX
That little hiccup just happens to be were the clip on fan is attached in a corner at roughly 23".
Now lets say I want to be at 16500 LUX @ 16"; (At a guess this is probably 300 PPFD or early veg, seems to be what the plants like, still in cups and only 2 nodes) to achieve this I had to reduce the power to 75 watts. Saving 25% electricity at the point of general uniformity. Take 16500/22000=0.75 bingo , pretty damn linear. Assuming I have done the calculations correctly as I suck at math
.props to @wietefras
A comparable chart that conforms to the Inverse square law would look like this.
https://imgur.com/a/jPwwynq
I think we can conclude that over distance you lose as much but you dont get that initial sag in a tent as seen in the second chart. I also bet that the larger the tent the more likely the losses would conform to the inverse square law, as would having point source i.e. 100 watt COB in this example, instead of a strip or QB type "panel of light".
Randomblame
Well-Known Member
12-18" is a comfortable height because you can reach to all the tops to work with them and it's close enough to waste only a little light on the walls; so a kind of compromise.
800μMol/s/m² seems to be the sweet spot without CO² but you can find a lot of peeps using more than that with success. It depends on what your goal is?
If electricity is cheap it makes sense to use 20% more light per sft to get 5% more yield. But if you pay +25ct/kwh or when they could catch you because of an excessive power consumption then it makes sense to use only as much as you need.
HPS cause eg. a typ. rash that is easy to identify for electricity suppliers and they know how it looks like from millions of streetlights. Hundreds were caught up this way where I live. When you have a 2 room apartment and have 5 times higher power draw like your neighbors or the previous tenant that can be a hint that you do something power intensive that's not allowed. With the new digital electricity meters that will soon become mandatory it will be even easier for them to see what type of device you are switching on and off when and how often.
You see, distance and intensity are often only personal preferences. If you can work well with 8"; perfect. And when power consumption is not an issue you can also use 80,000lx.
wietefras
Well-Known Member
@canadian1969 just showed that changing the height from 4" to 20" he went from 58000lx to 27000lx. ie he lost about half his light over 16".
See ledgardner's measurements of quantum boards. He also shows an average PPFD at 18" which is just over half of what the specs of those boards should produce according to the specs.
You really lose a large amount of light when you hang them too high for a "little" convenience of not having to move the fixture up and down for perhaps at best one time a week when you actually need to mess with the plants.
@SMT69, if you want to maximize then do so by lowering the light. If that's too much light then dim it.
SMT69
Well-Known Member
yeah thats what I would think right?
yet the only fat bud led grows (and there's lots of them now) im seeing all have um up pretty high and cranking them .......is there anyone whose grown some nice nuggs with led dimmed and slammed ? id love to see their journal
im just in early flower (3rd week) with mine, so I'm curious how the best led grows are doing it... thx !
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canadian1969
Well-Known Member
The other thing to consider is heat along with proximity. This thread also makes the case for more strips at lower powers so that uniformity is achieved within the shortest distance possible.
I am going to start my 2nd run with 16x EB2 (2ft) strips. Tent is 3ft high (there is also a carbon filter inside).
I was worried that 120-150w in a 2x3x3ft tent could have been on the low side but got a 1.3-1.5 gpw ratio and I am impressed, willing to see if the reduced gap between tops and lights could compensate for the overall low light output.
I was worried that 120-150w in a 2x3x3ft tent could have been on the low side but got a 1.3-1.5 gpw ratio and I am impressed, willing to see if the reduced gap between tops and lights could compensate for the overall low light output.
OLD MOTHER SATIVA
Well-Known Member
as close as i can
boilingoil
Well-Known Member
Somewhere between 6-12" seems to be my sweet spot at full power (268 watts)
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SMT69
Well-Known Member
Spectacular for such a small space , great coverage, amazing for a 3’ high tent
Epic fat buds, even the buds on the very edges are big
i saw the other posts of your colas, did you get 2g/w?
boilingoil
Well-Known Member
No, only 1.9 gpw. But I did get my standard 3 ounces a plant, with 21 days veg time.
wietefras
Well-Known Member
There is a practical limit on how low you can go though. At some point it becomes a nuisance and height differences in the canopy can prevent going too close.
Although for really small grows you can go lower, but for 3'x3' and up I wouldn't go lower than say 6" (or perhaps 4") and then you don't need that many strips to get decent uniformity. 4 double row strips on 3' is already enough to drop to 6" (and lower even).
I recently created a 4 row COB fixture (reusing 24 old COBs) in a 100x100cm (3' + 4") test tent and I drop that to 6" (15cm). It has a few cooling fans which spread the warmth from the leds onto the canopy. I feel that actually helps against top rot.
canadian1969
Well-Known Member
I'm not familiar with the term top rot, bud rot I am but thats a humidity issue. I was thinking heat stress/ bleaching or burning/drying out the tops, particularly with builds that do not have fans drawing heat up and away from the leds. I think 12-18" is reasonable, if a grower can get them closer then go for it. As Old Mother says.
Houdeeni
Well-Known Member
I’ve
I’m not running LEDs but will be running the nextlights LEDs by next year in our commercial grow facially (I live in Mi) which I understand to be equal or better than the hydrofarm phantom DEs I’m currently running.
My question/response is that I’ve always noticed in magazines and online pictures ligts are always way high up in the air and not the 2-3 feet away from the canopy.
I have noticed my plants suffer during the veg to bloom cycle shift (I have standard MH in my veg room). I’m starting to wonder if my lights are too close and/or too powerful because I run them at 1000w.
Thinking of running them lower and/or bringing them into bloom as shorter plants since I have low ceilings.
Any thoughts and suggestions would be really appreciated.
I’m not running LEDs but will be running the nextlights LEDs by next year in our commercial grow facially (I live in Mi) which I understand to be equal or better than the hydrofarm phantom DEs I’m currently running.
My question/response is that I’ve always noticed in magazines and online pictures ligts are always way high up in the air and not the 2-3 feet away from the canopy.
I have noticed my plants suffer during the veg to bloom cycle shift (I have standard MH in my veg room). I’m starting to wonder if my lights are too close and/or too powerful because I run them at 1000w.
Thinking of running them lower and/or bringing them into bloom as shorter plants since I have low ceilings.
Any thoughts and suggestions would be really appreciated.
torontoke
Well-Known Member
You’ve seen my journal and my leds are dimmed to about 60% and hang 8-10” above my canopy
Randomblame
Well-Known Member
It depends on the light source. An HPS is a strong 360° point with up to 2100μMol/s PPF and therefor you need some distance (and a reflector) to get a usable intensity level below them. Now imagine you would have 10pcs 100w bars with eliptical footprints and less intensity evenly spread across the canopy. You have much more even coverage (+80%) but with lower intensity and for this reason you even "need" less distance to get the same intensity levels. But if you reduce the height further you can even get higher intensities and still have good uniformity. With a HPS you would only create a center hotspot and get more shade in the corners. Now imagine too that LEDs produce light even more efficiently like HPS or CMH and you understand why the most gardeners switch to LEDs.
To use the full potential of such 1000w HPS bulbs I would use them in vertical orientation(hanging down from the ceiling) and without reflector. You only need a good fan blowing vertically to remove most of the heat and could arrange the plants aound them with only 12-18" distance. Sometimes 2 ft. cooltubes are used to place 2 bulbs inside and mounted vertically but I don't like them(only 90-93% transmission when clean). A strong fan does the same without a 2nd glass layer. I recommend to search the web or youtube to get a better idea. (HPS + vertically should be enough)
Or have a look here..
https://www.rollitup.org/t/strip-leds-in-the-garden-of-paradise.954799/page-7#post-13966706
zypheruk
Well-Known Member
Really nice setup similar in some ways to my own with the restricted height, considering the lights running dimmed the gpw ratio was bloody good to say the least. It gives me something to look forward to with my current grow so long as my strain is a good producer.
Cheers
How my grows looking so far, quantums on the top and Samsung strips on the lower level.
