BTU AC per 1000w cob?

Randomblame said:

Forget this! 12-15inch is way to less distance at such intensity and you will end up with getting massive bleaching. Get a cheap lux-meter and try to spread the light as much as possible for an even canopy coverage. Above 65.000lx(ca. 1.000μMol/s) it is really easy to get bleaching, also if you feed your plants with additional CO². Äquatorial sativas can handle intense light much better as a dutch outdoor indika for temperate climazones. So it's also strain dependent.

I would recommend to start with 24-30" and let the plants grow untill you see first signes of stress. Than rise the lamp a bit and keep that distance for the whole grow!

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Raising the lamp would be the same as just dimming them further.
If you can dim lights I don't see why anyone would raise lights when they can dim.

Reason I want to attemp to get them as close as possible is that I want nice long colas.

If you dim instead of raise them then you will be saving electricity

I also recommend to have a look at lukio's garden. He got massive yields also with distances of more than 24 inch. I'm sure, you can learn a lot and you will like his exceptional nice plant shots. He's really a photo artist and could easily make the cover pics for a 4.20 magazine!

https://www.rollitup.org/t/lukios-secret-garden.899450/

George2324 said:

If you can dim lights I don't see why anyone would raise lights when they can dim.

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better penetration

George2324 said:

What issues in flower are you talking about?

I've done several grows before. Plenty of experience and I've hit 1 gpw with hps plenty of times.

I'm just changing over to cobs.

I can get the portable ACs to remove 24000 BTU for 2600W. Not as good as a mini split but no other option in this case unfortunately

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Your a top grower then, I never hit 1gpw with hid, mag ballasts didn't help my cause ......or I just sucked

In your specific sealed room it's a good amount of wattage + the compressor(s) heat load from the crappy stand up AC units, + dehumidifier heat load?,etc............I would lower the light draw honestly, possibly same weight of the hps @ 20-25% less power with led.........or take a look at the 36k minisplit option again, it removes a decent portion of heat from the equation= the compressors out of the grow room. Should be fine with that if it's a straight 6k swap

REALSTYLES said:

You are going into winter and 24000 btu works for 4600k of cobs I know for sure I've flowered with a wall unit AC before and had to adjust the AC so the room wouldn't get too cold. Lets see what the others have to say about this pic of proof

View attachment 4024737

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he's planning on a 6000w SEALED room with hopefully decent insulation, winter might mean little..........and what about summer, forget the big investment ? lol

CobKits said:

better penetration

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You get better penetration by having lights higher?

Really? Doesn't seem to make sense to me?

George2324 said:

Raising the lamp would be the same as just dimming them further.
If you can dim lights I don't see why anyone would raise lights when they can dim.

Reason I want to attemp to get them as close as possible is that I want nice long colas.

If you dim instead of raise them then you will be saving electricity

Click to expand...

But at 12" and full blast you will end up with +2000μMol/s! That's why we recommend to use only 30-35w without and 40-50w/ft² with CO². And... Dimming is not the same as rising the lamp. If so, we would use 2" distance but only 100w/m². Rising the lamp means not the light is lost, it will be reflected and bounced back to the plant. The goal is to spread the light as even as possible above the canopy to avoid hotspots. The better you do this job, the lower can be the distance to the lamp. Best is to get a $10 lux meter from e3ay and try to get 50.000-60,000lx over the entire canopy area but avoid hotspots above 60.000lx in the same time.

Randomblame said:

But at 12" and full blast you will end up with +2000μMol/s! That's why we recommend to use only 30-35w without and 40-50w/ft² with CO². And... Dimming is not the same as rising the lamp. If so, we would use 2" distance but only 100w/m². Rising the lamp means not the light is lost, it will be reflected and bounced back to the plant. The goal is to spread the light as even as possible above the canopy to avoid hotspots. The better you do this job, the lower can be the distance to the lamp. Best is to get a $10 lux meter from e3ay and try to get 50.000-60,000lx over the entire canopy area but avoid hotspots above 60.000lx in the same time.

Click to expand...

If you have 4 cobs per square foot though the light should be already very well spread across your canopy.

For every 12 inches away from the plant the usable light drops by half.

I'm gonna get a par meter hopefully soon and I'll do tests on it all and see how it goes.

I'm building a vertical system with cobs and plants mounted vertically I will have enough room for 1m tall plants and 14 inches to the cobs.

Only way I can increase distance from cob is to grow smaller plants and I have heat sinks mounted back to back vertically.

I'm exited to get this going I just have to finish building my custom cob Fixture... 100 cobs out of 320 to go

George2324 said:

You get better penetration by having lights higher?

Really? Doesn't seem to make sense to me?

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Indeed, it sounds strange on the first view but it makes sense!
More diffuse light penetrates deeper as more intense direct light. That's one of the reasons why Quantumboards and LED strips are so efficient or why diffuser sheets are use in greenhouses.

George2324 said:

You get better penetration by having lights higher?

Really? Doesn't seem to make sense to me?

Click to expand...

inverse square low
if you have 1000ppfd at 24 inch from the light source (any light source ) than at 48 inch you will have 250 ppfd (1/4).
if you have 1000 ppfd at 12 inch (light dimmed and more close to plants) you will have 250 ppfd at 24 inches .
i think thats what cob kits was referring to as penetration .

kony brado said:

inverse square low
if you have 1000ppfd at 24 inch from the light source (any light source ) than at 48 inch you will have 250 ppfd (1/4).
if you have 1000 ppfd at 12 inch (light dimmed and more close to plants) you will have 250 ppfd at 24 inches .
i think thats what cob kits was referring to as penetration .

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Ah right I get that. The distance required for the ppfd to drop would be larger so more light gets further down the stem.

Does excess light manage to actually get through leaves though? If you have a full canopy can the leds be powerful enough to travel through a leaf?

George2324 said:

If you have 4 cobs per square foot though the light should be already very well spread across your canopy.

For every 12 inches away from the plant the usable light drops by half.

I'm gonna get a par meter hopefully soon and I'll do tests on it all and see how it goes.

I'm building a vertical system with cobs and plants mounted vertically I will have enough room for 1m tall plants and 14 inches to the cobs.

Only way I can increase distance from cob is to grow smaller plants and I have heat sinks mounted back to back vertically.

I'm exited to get this going I just have to finish building my custom cob Fixture... 100 cobs out of 320 to go

Click to expand...

Oh man!!!
If you have such concrete plans and already knows, which LED's and what you want to use everything, why did not you say it from the start.

All info's come poé á poé ...
It would have been much easier if you had communicated all the information at the beginning.
If you have 7m² but plan to grow vertically on let's say 6' tall walls, it changes everything...
Unfortunately it will be time for me to go to bed, but I'm sure you'll have lots of fun with your setup.
For today ... adios muchachos!

George2324 said:

Ah right I get that. The distance required for the ppfd to drop would be larger so more light gets further down the stem.

Does excess light manage to actually get through leaves though? If you have a full canopy can the leds be powerful enough to travel through a leaf?

Click to expand...

Some does but not much ,you will have shade down the plants like hps,its a bit better because of the green parts of the spectrum that led has and hps has less,so just a little beter with led.
i grow small plants,50-55 cm high ,16 per meter square ,and still defoliate them as i would with hps.i highly recommend it .
thank's

Randomblame said:

Oh man!!!
If you have such concrete plans and already knows, which LED's and what you want to use everything, why did not you say it from the start.

All info's come poé á poé ...
It would have been much easier if you had communicated all the information at the beginning.
If you have 7m² but plan to grow vertically on let's say 6' tall walls, it changes everything...
Unfortunately it will be time for me to go to bed, but I'm sure you'll have lots of fun with your setup.
For today ... adios muchachos!

Click to expand...

I sometimes figure posting my whole design confuses things when i figured a simple wattage question was easy

How does it change everything? I don't think of it as any different I just view my wall as the canopy instead of of the floor.

One side is 1.2m high and 3m long and the other side is 1.2m high and 3m Long total canopy area 7.2m

Lights mounted vertically in the middle
4 cobs per square foot I went for this for the best coverage

George2324 said:

Ah right I get that. The distance required for the ppfd to drop would be larger so more light gets further down the stem.

Does excess light manage to actually get through leaves though? If you have a full canopy can the leds be powerful enough to travel through a leaf?

Click to expand...

Only a minor part gets through the leaves, the most is reflected be other leaves. Thats the reason green light is mostly used in deeper plant sections.
Inverse law applies only to open areas, at least in the way you tell it. As soon as walls are present, it loses its relevance, since most of the light is not lost but reflected.
If you double the distance within a tent or a sealed white room, you lose much less than you believe. Again, I recommend @lukio's garden to see what distances are possible.
Do you reall think you will lost 75% of your light if you double the distance from 12 to 24"? That's only possible with matt black walls and no reflecting area underneath the light.
Good night!

George2324 said:

You get better penetration by having lights higher?

Really? Doesn't seem to make sense to me?

Click to expand...

yes.

a light 24" above the canopy casting 1000 ppfd at canopy will have a much more intense ppfd 12" into canopy than a light 3" above canopy casting 1000 ppfd at canopy

inverse square law

its why outdoor plants get intense light top to bottom, there is literally no drop off in intensity adding 5 more feet to 93 million miles

CobKits said:

yes.

a light 24" above the canopy casting 1000 ppfd at canopy will have a much more intense ppfd 12" into canopy than a light 3" above canopy casting 1000 ppfd at canopy

inverse square law

its why outdoor plants get intense light top to bottom, there is literally no drop off in intensity adding 5 more feet to 93 million miles

Click to expand...

Right I'll see what I can do to increase canopy distance but there's no way I'd be able to get it to 24 inches that would only give me enough space for 30cm tall plants

One benefit of growing vertical the plants grow at a 45 degree angle so a 100cm plant only reaches 70cm to the cob.

I can grow my plants to 2 foot tall and get 18 inches from cob to canopy. That's probably my best option

Hopefully that will allow me to get 2ft long colas

So theoretically if I adjust my watts to produce 1500 ppfd At 18 inches I should get a decent ppfd a further 18 inches down

Thanks @Randomblame very kind.

I can do pretty pics but i cant do the science - so i'll leave that to you guys

They love the distance @George2324 took me a while to realise this

George2324 said:

Ah right I get that. The distance required for the ppfd to drop would be larger so more light gets further down the stem.

Does excess light manage to actually get through leaves though? If you have a full canopy can the leds be powerful enough to travel through a leaf?

Click to expand...

Some does but not much ,you will have shade down the plants like hps,its a bit better because of the green parts of the spectrum that led has and hps has less,so just a little beter with led.
i grow small plants,50-55 cm high ,16 per meter square ,and still defoliate them as i would with hps.i highly recommend it .
thank's

George2324 said:

I can grow my plants to 2 foot tall and get 18 inches from cob to canopy. That's probably my best option

Hopefully that will allow me to get 2ft long colas

So theoretically if I adjust my watts to produce 1500 ppfd At 18 inches I should get a decent ppfd a further 18 inches down

Click to expand...

theoretically yes,you will get 1500/4=375ppfd