Grow light height mystery

DaFreak

Well-Known Member
Ok so here is a question for you guys. I always used a chart similar to the one below when hanging my lights before when I started out and haven't measured actually distance in forever, just read the plants, but over the years have seen so many successful beautiful looking grows with their lights hanging way higher than what I thought would even work, like sometimes 4 feet above canopy. For example my new cobs say 18 inches from canopy but I see people with blurples hanging 4 feet up. What gives?


Grow LightClosest~ SunlightFurthest
150W8″ (20cm)10″ (25cm)12″ (30cm)
250W10″ (25cm)12″ (30cm)14″ (35cm)
400W12″ (30cm)14″ (35cm)19″ (48cm)
600W14″ (35cm)16″ (41cm)25″ (64cm)
1000W16″ (41cm)22″ (55cm)31″ (79cm)
 

TheDifferenceX

Well-Known Member
18'' is not a bad height at all.

I have a window A/C in my grow room so i tend to keep it closer to 12'' away. That's really what it comes down to, what are the temps like inside your growing area? That is the deciding factor in how close you can keep the lights.

4' is absurd.
 

getogrow

Well-Known Member
This highly depends on your method and your lighting. A new light with samsung diodes will be much brighter then what your used to. With HID lighting , it was "get um as close as you can without heat issues" ....that does not work with leds. Ive never even seen a real case of light bleaching until these leds came out.
So with a good light you can probably get close to 18" or something but if your switching from HID then that is going to be too bright for your "norm". I know guys who do 5ft and guys who do 12". (the guy that grows um at 5ft grows much better but not because of the light)

That chart says "furthest" for a 1k= 31" ....no , not at all. A 1k hps can flower plants at 7 ft off the canopy but its not "optimal". And some folks on here think that 16" on a 1k would kill them.....it completely depends on your method an lights!
 

OneHitDone

Well-Known Member
The old Blurples also probably have lenses focusing the light like laser beams so gotta hang em high yet still only cover an area the size of the box they are in :peace:
 

Kalebaiden

Well-Known Member
I have insane air flow in my tent and the room is cooled through AC, my plants got within 3" of my 250w and are fine.

I moved the tops so they're 6" away and everything is still fine.

Edit*
I use HPS
 

Medskunk

Well-Known Member
Doesnt co2 help for lights closer?

If i take my optic2 any closer than 28" atm the canopy gets all weird.
 

Kassiopeija

Well-Known Member
It depends on your footprint, closed or open environment, and from how many sources the light is emitted.


You don't have to match the suns output either, as this is a completely different and variable spectrum, not even CO2 growers go up to 2000ppfd

Hope this helps
 

getogrow

Well-Known Member
So I still don't get how people hang HPS 1000 at the ceiling and get good grows
Because they are much brighter then the charts show. im watching a friend grow with his leds on the ceiling and hes doing good. (im talking 5+ foot to the canopy.) i KNOW i could leave my 1k's up high but the grower in me wants to lower um everytime i can. It shows everytime too.... there is always a hotspot in the middle of the 1k. It dont hurt much overall but the middle always wants more food then everything on the outside of the middle.
 

Lockedin

Well-Known Member
Ok so here is a question for you guys. I always used a chart similar to the one below when hanging my lights before when I started out and haven't measured actually distance in forever, just read the plants, but over the years have seen so many successful beautiful looking grows with their lights hanging way higher than what I thought would even work, like sometimes 4 feet above canopy. For example my new cobs say 18 inches from canopy but I see people with blurples hanging 4 feet up. What gives?


Grow LightClosest~ SunlightFurthest
150W8″ (20cm)10″ (25cm)12″ (30cm)
250W10″ (25cm)12″ (30cm)14″ (35cm)
400W12″ (30cm)14″ (35cm)19″ (48cm)
600W14″ (35cm)16″ (41cm)25″ (64cm)
1000W16″ (41cm)22″ (55cm)31″ (79cm)
Assuming each light is the same wattage / intensity:

Point Light / Single source lights - COBs & HIDs & narrow qb's - "hard" light, distinct, hard lined shadows, good penetration, poor coverage / spread.

Soft Lights - Bars, larger boards, and combinations - Soft to no shadows, shadows wrap around curved objects, less penetration, excellent coverage / spread.

Diffused lights / reflectors / bounces - we don't use these as sources, but reflective surfaces (Tent walls, panda film, etc.) act as bounces & reflectors for us.

Point lights and boards like my cheap chinese burples create pools of intense light that fall off quickly.
Soft lights spread evenly but lack the intensity of point lights - UNLESS you use more wattage to achieve the same intensity over the whole canopy.

My DIY dreams right now are per-plant COBs, with strips / bars lower and angled for optimum coverage.
 

Kassiopeija

Well-Known Member
My DIY dreams right now are per-plant COBs, with strips / bars lower and angled for optimum coverage
Malocan made quite some tests with COBs and one could gather from his pics it's actually a good idea to take away the reflector and have the COB light more dispersed, which may enable one to put it more close, if one doesn't have necessary height, or proper reflective material.
The angled sidelight is one road I currently pursue in a DIY project.
 

Lockedin

Well-Known Member
Malocan made quite some tests with COBs and one could gather from his pics it's actually a good idea to take away the reflector and have the COB light more dispersed, which may enable one to put it more close, if one doesn't have necessary height, or proper reflective material.
The angled sidelight is one road I currently pursue in a DIY project.
Makes sense - especially in a tent with reflective walls in close proximity.

I still might try a reflector on a COB if my plants are inside the pool - less redirected photons.
Since the flowers & leaves would have strong, direct light from the COB, albeit at a near straight down 90 degree angle;
- and healthy branches (or trained) point up at an roughly 45 degree angle;
- why not tune the angle of the bars / boards and decrease the shadow count on the canopy (as opposed to just more is more)?

- could even tune the freq. if simple dimmers are used
- cobs at 3500 or 4000K, and strips / bars at 1750 or 2700K.
- For the "mimic nature" purists this would emulate sunset conditions too. :bigjoint:

edit - sorry, got more into design than "how high"
 

Bookush34

Well-Known Member
I have 13 COBs in my 3x3 tent.
Cranked up its close to 1100watts. Which will nuke my plants.
But I run them at 30” above the canopy and dimmed to 25%~ in veg and around 50-60%~ in flower.

Getting great efficiency out of the lights and amazing light coverage.
 

Renfro

Well-Known Member
I have 13 COBs in my 3x3 tent.
Cranked up its close to 1100watts. Which will nuke my plants.
But I run them at 30” above the canopy and dimmed to 25%~ in veg and around 50-60%~ in flower.

Getting great efficiency out of the lights and amazing light coverage.
This is an excellent approach. The light hits the plants at more angles since you have more points of emission. Add to that your getting great efficiency. A very good approach, of course that's an investment in COB's but you get what you pay for right?
 

Bookush34

Well-Known Member
I
This is an excellent approach. The light hits the plants at more angles since you have more points of emission. Add to that your getting great efficiency. A very good approach, of course that's an investment in COB's but you get what you pay for right?
I have a 5 cob air cooled hood I built with vero29s. Then I have two 4 cob bars hanging on the edges at a 45* angle to get some more penetration from the side
The cob bars are citizen 1212.
Mix of 3000k and 3500k.

Yes a bit of a investment. But I do pull the cob bars out in the spring and use them for starting my outdoor veggi garden as that what I originally bought them for. Hate to see them sit unused for 10 months of the year.
 

Lockedin

Well-Known Member
I

I have a 5 cob air cooled hood I built with vero29s. Then I have two 4 cob bars hanging on the edges at a 45* angle to get some more penetration from the side
The cob bars are citizen 1212.
Mix of 3000k and 3500k.

Yes a bit of a investment. But I do pull the cob bars out in the spring and use them for starting my outdoor veggi garden as that what I originally bought them for. Hate to see them sit unused for 10 months of the year.
Great sounding setup!

Is the 5 COB hood a "per plant" type setup?
 
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