Light degradation -Opinions?

[Stilletto]

I have prolly read every post on this forum and yet I still have a question, or at least I am looking for some opinions.
My question revolves around light/distance degradation between a 400 watt bulb and 1000 watt bulb. I use 2 400w hps and keep my top buds about 4" from the shade glass. A friend is using a 1000 watt for same area (5x4) and has to keep his plants about 1-1.5' away from glass.
Now we know light degrades at aprox 25% per foot. So at even one foot away he is getting 750watts of usable light to my 800. Also since his light is centered and this makes the farthest parts of the room at a greater distance than my 2 400's spread over a larger area, therefore reducing usable light even more.
So I beleive that 2 400's will give more usable light in an equal space as 1 1000w.

Thoughts? Ideas? Opinions?

Jonny

 

[PrairiePoet]

Without laying out a grid and using a light meter, I would think hard to say right off. Who is going to get the bigger harvest with all other variables the same... ???

Though my thought is he would get deeper penetration of the canopy in the middle, and larger buds in the middle. While you would get larger buds out on the edges.

just my $0.02

Prairie

 

[Stilletto]

Re: Light degradation -Opinions? Now with crude charts and math!

Well I ordered a light meter and in the mean time I have been doing alot of research on this topic as well as light in general.
I will say that I stand by my above theory but will concede that a air cooled 1000w would probably give 10-20% more efficiency just due to the fact that even though the heat would be more I doubt very much that it is double. I can discuss this more if someone wants.

What I want to discuss at the moment is efficiency of a light vs a given space. I started thinking about light movers and wanted to know if they are more or less efficient than steadyéfixed lights.
For these equations I am not useing watt measurements I am using "efficiency percentages". A bulb of any size that is as close to a plant as possible without burning it will be considered 100% efficient. The further away it is will make it less efficient by a percentage. It is widely recognized that this is the standard equation....

WPSF assumes that the bulb's intensity is equal over the entire grow area.. in other words each square foot/meter receives the same number of lumens. But in reality light diminishes rapidly the farther you go from the bulb (1/4 the intensity for each doubling of the distance). So each bulb has a limited range, beyond which you do not have good growth.

Taken from this post...
Jackerspackle's Lighting Coverage Primer

So using this information I came up with the following chart. Now keep in mind that I wasn't looking to break it down into large fractions or decimals but just close enough to draw a conclusion. When I get my light meter I will do more accurate testing.
Description of this chart:
Each square equals 1'x1' so the hypothetical rooms are 5'x5' and bottom ones are 10'x5'.
The lights shades are outlined with dots and the area directly under the bulbs is shaded and for this test represent 100% efficiency.
The percentages were added up and divide by the square foot for overall efficiency.
Chart #1: 1 bulb in 5x5 room - 63.2% efficient.
Chart #2: 2 bulbs in 5x5 room (accounting for overlap) - 72% efficient
Chart #3: 1 bulb on light mover in 5x5(traveling 2' each way) - 50.1% efficient
Chart #4: 1 bulb in 10x5 with light moverTraveling 7') - 39.1% efficient
Chart #5: 2 bulbs in 10x5 fixed (no mover) 63.2% efficient.

I would still like to get some input from others or any thoughts you might have.

Jonny

 

[Stilletto]

Really? No thoughts?
I expect my light meter in a few days and will do some tests on 400/1000 watt systems and different reflective materials tansfer of light through green matter etc.... Gotta do something while the ladies grow

Jonny

 

[Stilletto]

So I figured I would post my conclusions since no one has any comments.
As demonstrated above, a room with a light mover is far less efficient than a room without a light mover. Although you may be able to grow more plants clearly they would not grow as big as they would under a fixed light. In a 10x5' room if you grew 10 plants (assuming 1oz per plant) you would get 10oz's. In a 5x5' room growing 5 plants, they would by the same equation yeild 1.7 oz's per plant for a total of 8.5 oz's. Clearly you would use half the amount of water nutes and time.
My fanal conclution at this time is that light movers are a waste of time, money and energy.

Any thoughts?

Jonny

 

[oldgardener]

Stilleto,
You have given some interesting food for thought here....
As I understand it, the light intensity decreases as an inverse square.
So the light at 1ft is 1/2 the light at 6 inches.
The light at 2ft is 1/2 the light at 1ft.
4ft is 1/2 of the 2ft intensity and so on.

Also, lumens per watt of each bulb size/type/brand has to be considered.
And how the output spectrum matches the PAR (photosynthesis) Nano meters.
If manufaturer "A" has a 3000k but can't provide a spectroscopic report, and manufacture "B" has a 3000k with a good spectrum that is in tune with the PAR, then I would guess that in most cases, "B" is a more effective and efficient choice for growing plants.

And something that doesn't get enough attention is the reflector.
Remember that only a small amount of the light is going down directly from the bulb. The rest must be reflected down..... and ideally that is not just back into the bulb.
Just more food for thought...
peace

 

[woods brother]

I am with the oldgardener. In my experience swapping reflectors and hitting the same space with the light meter can make HUGE differences. A quality reflector that gets light away from the "shadow" of the bulb, but still focuses the light to your growing area can make a huge difference. I think the information you have provided is really useful and if you would drop a picture on the thread along with your reflector type and bulb it would be even more useful information.

 

[Stilletto]

I apreciate your opinions and thoughts on the issue. I agree that "light" has many issues such as lumens, color spectrum, par etc and reflectors are all variables. I would like to discuss them more, as I find that there are always ways to improve yeilds.
A friend one told me "if you can find 100 ways to increase your yeild by 1% then you will double your harvest."
Some people just half-ass stuff and then ask how to get bigger harvests. So many over look simple things.

I use 2 different air cooled shades in my room, a new sunstar "dimpled" reflector and the other is an older "chrome" finnish. The dimpled one clearly is brighter and produces better. I will be replacing the older one soon.

Jonny

 

[Grandpappy Sr]

I like to "just half-ass stuff", DO wap do doo.

 

[Hogdady]

So I figured I would post my conclusions since no one has any comments.
As demonstrated above, a room with a light mover is far less efficient than a room without a light mover. Although you may be able to grow more plants clearly they would not grow as big as they would under a fixed light. In a 10x5' room if you grew 10 plants (assuming 1oz per plant) you would get 10oz's. In a 5x5' room growing 5 plants, they would by the same equation yeild 1.7 oz's per plant for a total of 8.5 oz's. Clearly you would use half the amount of water nutes and time.
My fanal conclution at this time is that light movers are a waste of time, money and energy.

Any thoughts?

Jonny

Did you adjust for the fact that with a mover, you can reduce the light to plant distance? I can get my 1kw's as close as 4 inches with a mover.....

 

[Stilletto]

Thanx for the continued thoughts.
Hogdady, yes I did account for the reduction in heat, in that I didn't account for any variables at all. I will explain; If your light is 4" closer then that will give you "your" 100% efficiency when lights are directly above your plant.

I am using "efficiency percentages". A bulb of any size that is as close to a plant as possible without burning it will be considered 100% efficient. The further away it is will make it less efficient by a percentage.

So the relector choice also falls into this. If "any" watt, reflector,spectrum, etc is used it will apply to the above quote. This is just a basic breakdown of how a light mover is less efficient use of available light under any circumstance. I am not "hating" on movers, just wanted to do the math and see how it figures into the equation.

I am also not saying I am 100% correct here, that is why I appreciate the feedback.

Jonny

 

[Hogdady]

My fanal conclution at this time is that light movers are a waste of time, money and energy.

Any thoughts?

Jonny

I don't understand how you can apply your findings to make this statement. They may be "inefficient" by your own definition, but that is a huge jump to say they are a waste of time, money and energy in relation to plant growth and yield....

 

[Stilletto]

I don't understand how you can apply your findings to make this statement. They may be "inefficient" by your own definition, but that is a huge jump to say they are a waste of time, money and energy in relation to plant growth and yield....

I guess I was a bit... preclusive.

What I meant to say is... according to the math, the further the light source from the plants, the less "efficient" the light source becomes. So when any given area exceeds the point to which the light source becomes "inefficient", it is then better (more efficient) to install a 2nd light source as opposed to using a mover. This will then apply as I stated above that using a light mover will yeild less in a room(ex. 10x5) than using 2 lights to cover that given space.
That make more sense?

Jonny

 

[Hogdady]

I guess I was a bit... preclusive.

What I meant to say is... according to the math, the further the light source from the plants, the less "efficient" the light source becomes. So when any given area exceeds the point to which the light source becomes "inefficient", it is then better (more efficient) to install a 2nd light source as opposed to using a mover. This will then apply as I stated above that using a light mover will yeild less in a room(ex. 10x5) than using 2 lights to cover that given space.
That make more sense?

Jonny

What you are saying is understandable, within the context of your calculations. But, with so many other variables that you haven't accounted for, it would be presumptive to correlate your results to actions like growth or yield.

 

[Stilletto]

What if I added - "Assuming all variables are equal."

Jonny

 

[oldgardener]

What you are saying is understandable, within the context of your calculations. But, with so many other variables that you haven't accounted for, it would be presumptive to correlate your results to actions like growth or yield.

Hogdady....That is a valid point, and all things being equal....they never are
We all need to remember that growing plants are not some sort of black/white right/wrong equation, but are part of a larger puzzle that includes lighting efficiency.

Stilletto, I like the way you think.....keep posting. There is no reason to keep doing things the "old way" just because that is how we have always done it.
Especially with the price of electricity and trying maintain a low profile with a goverment that still fights battles against those who choose to use the herb.
peace,
an old gardener

 

[woods brother]

What you are saying is understandable, within the context of your calculations. But, with so many other variables that you haven't accounted for, it would be presumptive to correlate your results to actions like growth or yield.

I love how society tends to think we are all a bunch of burnt out idiots, sitting around looking at each other and saying Whaaaat?

 

[Hogdady]

What if I added - "Assuming all variables are equal."

Jonny

That certainly adds credence to your findings. But applying that to make real world decisions without further consideration of the variables, imho, would be short minded.

 

[Hogdady]

We all need to remember that growing plants are not some sort of black/white right/wrong equation, but are part of a larger puzzle that includes lighting efficiency.

That would, however, require a standardized definition of "efficiency", would it not?

 

[medme]

i like a light mover,,, the light can be closer because its moving all the time.... and they work GREAT...