Scrog screen distance to bulb?

[Power13]

I am interested what everyone's opinion is as to the distance from the bulb in a vertical scrog. The reason this question is asked, is because we need to know the radius for our vertical circle (octagon, etc). The bigger this radius, the more screen area to fill in, and the more potential yield.

Another related question, does using a vertical stack of lights, affect this distance? If so, how and why?


Here is my opinion

250: 12 inches

400: 18-24 inches

600: 24-30 inches

1000: 30-36 inches


I think that if you use vertical stack of lights, you should stick with the further distance, since your overall lumens are increased due to the lights bring close to each other.

 

[Hundred Gram Oz]

Hey Power whats up bud? I have a few questions first, how many plants are you looking to grow? How many levels will your octagon have? Will you have a fan under your bulb? Just trying to get an idea of your setup

Here is a good chart for information regarding distance from the bulb, remember one of the main advantages of vertical growing is that you have the ability to put plants much closer to the bulb without burning them, thus boosting your yield, you will be able to put put plants much closer that what you have written but I also understand that the bigger the radius means more plants being able to fit around the bulb....... Take a look at these 2 charts.

If you have a 600w bulb with a fan below it you can get your plants as close as 6 inches from your bulb, but at this distance the bulb will bleach your plants from too much intense light, I prefer to keep the canopy 9-10 inches from the bulb.

In reference to the chart above a 600w at 24-30" away from your canopy will give you 7-10 w/SF, if you compare this to 10" you will see that it's 70 w/SF.

Chart 2

A 600w bulb at 24-30" away from your canopy will give you, 7,321 - 4,686 directed at your plants which isn't much, Especially when you consider if you had your bulb 10" away from your canopy, which would give you 42,170 directed at your plants.

What I'm trying to push is that Lumen's quickly diminish the further distance they travel and since your going vertical you may as well get the most out of them BUT it's your decision and every grower will do what they feel is right for them.

 

[Hundred Gram Oz]

Yeah obviously the lumen's don't disappear but the point that I was trying to make is when you spread them out over a larger area your hitting you plants with less effective light, I don't think anyone would disagree with that? The whole point of growing vertically is to be more efficient in the way you use your light, so you can max it out and get a higher gpw. The next big benefit is the space it saves you, which some might consider an even bigger benefit.

 

[Power13]

Hundred Gram OZ,

Thanks for the reply bud, big props for the pretty posters.

My setup is detailed in a thread I have in the vertical forum, its basically a collosal cage setup with 6 foot diameter between tubes (mine can be moved in or out if needed to create more space, or make less). I have 3 digital 600's in cool tubes lighting up about 7 feet of height. I have thought of upgrading to 1k's for this space, but we'll see. With cool tubes, and proper air extraction, heat is not a problem anywhere near the cool tubes. I can safely put my hand on the tube, and hold it there with no problems, the glass is cool to the touch, barely even warm.

As for a little more info about my thought process here. I think to fully take advantage of vertical, you need to fill in as much space around the bulbs as you can get. I think that a plant thats scrogged will still stretch past the screen, at least the way I have grown it. I haven't tried in vertical, so I'm not sure how far this stretch will be, but I think its safe to assume 6" of stretch on most strains.

Thus wherever we place the screen, the actual buds will be closer to the lights.

Based on your top graphic, it seems to suggest placing the buds at 12 inches from a 600 watt, in order to get 50 watts/SF. So to me, the scrog screen itself, should be at least 6" back from that, this puts it at 18" from the light itself. Somehow this still seems close. My reasoning is based on personal experience and growing plants in scrog.

I think that 24" or 2 feet, allows up to 1 foot of stretch from the scrog screen for the buds to get optimal light, this seems like a good compromise.

What do you think?

 

[Hundred Gram Oz]

Power I gotta run Buddie but I'll more than likely be online tonight to ans all your questions

smokinshogun I think your just a troll, I noticed that you are one of the 3 people that voted against ICM having a vertical section, is there any reason in particular why you voted against the members having their own vertical section to forum?

 

[Teeg420]

You know whats funny with the 1K's IME is that you can put your hand on the tube and its cool but take your hand 6" to 12" away and you can feel the heat radiating, thats why i feel its really important to have a good fan below pushing that air/heat up away from the canopy.

600's different story havnt ran those in a long time, so i dont know if you have had similar experiences with it.

 

[Teeg420]

cant see any of smoking shoguns comments, did he delete his post?

 

[TwinTurboGuy]

Here is my take on light distances in vertical setups. When H G 4 2 0 . com was still around, I had my chance to speak to Heath Robinson about his light setup. His key to superior yields was to use bare 600 watts over 1000. Because the 600s radiate less heat, the closer you can have your plants. Cool tubes are not necessary in a setup like this, and the glass diffuses plenty of the light.

Most successful growers stack 600s rather than 1000s. Although 1000s can have more coverage in a dense canopy, 2 600s would definitely put out more overall. Not only it can cover more plant matter, but both bulbs radiate heat in two different areas, as opposed to a 1000 that is concentrated into one bulb. This concentration of heat really limits to how close you can bring your plants, and a cool tube might be needed in such a situation. There may be some exceptions to keeping a farther distance from the bulb if you use multiple 1000 watters to overlap each other (one example is a stadium setup).

Of course, overtime, it takes awhile to understand how close you can put them as one grower can adjust to it and what temps the plants are accustomed to.

 

[Teeg420]

true, but i have always loved the girth/bud density of 1K's, not that I havn't gotten huge colas of my 600's i just prefer the 1k's. Plus that amount of extra money spent on 600's i cant justify, just to use 400 watts less than 1ks when running close to 9,000 watts. I understand 600's radiate less heat but you almost end up spending double cause 600's are 10 bucks less than 1K's retail for. Also I have noticed a lot of europeans and canadians use the 600's.

I do like the idea of spreading out the concentration of the light/lumens more with the 600's.

I have thought about running a couple of 600's just for fun cause its been awhile.

IME to each their own, whatever works for you.

 

[Power13]

Guys, this room will have aircooled lights in cool tubes, because its a sealed room with co2, a/c, dehumi, etc.

 

[McSnappler]

I've been pondering the question for 400 watters. The useful range of light is 6"-18", but at 18" the lumens have fallen off massively.

It's a tradeoff between more square footage of screen, and more light intensity for that screen.

I'm leaning towards moveable screens that are 14" away from lamp once all "pieced together". Hopefully if individual screens have shorter/longer colas than the average, I will have enough room to move the screens about slightly.

 

[Power13]

I've been pondering the question for 400 watters. The useful range of light is 6"-18", but at 18" the lumens have fallen off massively.

It's a tradeoff between more square footage of screen, and more light intensity for that screen.

I'm leaning towards moveable screens that are 14" away from lamp once all "pieced together". Hopefully if individual screens have shorter/longer colas than the average, I will have enough room to move the screens about slightly.

18" seems like a good place for your plants to start working there way towards the bulb. My whole thought is that your plants should stretch from the screen a little bit. Remember we are trying to place the buds themselves into the optimum max lumens position, not the screen. The screen should be behind most of the buds on your plants.

 

[McSnappler]

What I worry about is setting the screen too far back, letting the plants get bigger than maybe they need to be, and having loads of budsites just in front of the screen that aren't getting any light through to them because of the dense forest up top hogging the bulb.

 

[Power13]

Thats not necesarily a bad thing, we are only talking inches here, and the back sides, that are not getting light can get trimmed at weeks 3 and 7. Thats how the cage and cube sog is done, I don't see why we couldn't do a filled in scrog in a similar way.

Only thing is, optimally, we should only be trimming behind the screen, and in front of it, it shouldn't extend more than what the bulb can penetrate. How far into a canopy can a 400 penetrate?

Something about your phrasing is making me doe-eyed. Dense forest of nugs you say in front of the bulb

 

[McSnappler]

The other concern would be the reverse.. If you set up your screen to be a max of 18" from the bulb without the ability to get any closer, what if you then find out, well into a run, that it's not close enough, the colas aren't long enough to benefit from full lumens?

 

[Power13]

The other concern would be the reverse.. If you set up your screen to be a max of 18" from the bulb without the ability to get any closer, what if you then find out, well into a run, that it's not close enough, the colas aren't long enough to benefit from full lumens?

To me that just sounds like you should setup several screens at different distances the first time, and see what you get. As in, you don't run a full system, but run it in a way that fits whatever distances to the screen make sense.

Then you use the results to fine tune your system for the 2nd run.

Another option is of course the good ole light meter, to tell us exactly where the buds need to be. I've been meaning to order one up, but haven't gotten around to it yet

 

[C21H30O2]

I use a screen with 20 inch diameter so that means buds are less than 10 inches from the plant, this is with dual stacked 600s. The plants are happy at this distance but too close (inside the screen) and they bleach the buds.

 

[TwinTurboGuy]

I've been pondering the question for 400 watters. The useful range of light is 6"-18", but at 18" the lumens have fallen off massively.

It's a tradeoff between more square footage of screen, and more light intensity for that screen.

I'm leaning towards moveable screens that are 14" away from lamp once all "pieced together". Hopefully if individual screens have shorter/longer colas than the average, I will have enough room to move the screens about slightly.

Have you looked into 400 watt CMH bulbs? I can't stress enough how great these bulbs can be. Many growers really overlook its advantage. Besides the better spectrum, same lumun output as an HPS, and less heat, its real advantage is how close you can bring your plants to it.

 

[oregon bob]

All this discussion over distances... never could settle this in my head, so...

Does anyone have any scientific data regarding how much light mj can use? I get this is dependent upon a number of factors, e.g., temps, nutes, co2, rh, etc, but does anyone have any real data? I haven't ever seen anything...

The closest i've found dated back to '87 from Daniel Storm... has a chart in his book correlating light intensity & co2 levels to plant growth rates. No raw data, but the chart indicates that diminishing returns are reached at appx 6500 lumens x 1300 ppms co2... anything over & above has very little impact to maximum growth rates.

With this in mind, what exactly would the benefits be of placing the plant tops so very close to the light such that 40k lumens is achieved??? Is it really doing anything of benefit, or perhaps even slowing "ideal" growth rates?

The benefit I've always noticed was plant canopy density & overall footprint maximization. These two components to verti output is dependent on casting a wider arc of light... 360d in fact. So, if you had stacked 1000's, or even a single, you will get more footprint by having the bulb 2' feet away vs 12". The 2' will have more plant canopy available & will still over saturate the canopy w max usable lumens.

Is this way off base?!? Peace.

 

[Bush Dr]

From experience
250 - 12" diameter
400 - 14"
600 - 16"
That's the diameter of the lamp 'scorch screen' inside that they scorch, pull them off a bit and all is OK

Been doing this for years

Bush