Light Penetration?

[Ranger]

2 - 400s are spread out. If you had a fixture with 2 400s in it, side by side, then you would get more penetration. Or if you had an 800w bulb. The 800 watts is spread out, giving you no more intensity. -granger

actually not. if you had two flashlights, one would light a beam 100 foot long and the other would lite a beam 100 foot long , do you really think if you held two of them side by side they would magically light a beam 200 feet long?

things to ponder eh.

 

[EclipseFour20]

actually not. if you had two flashlights, one would light a beam 100 foot long and the other would lite a beam 100 foot long , do you really think if you held two of them side by side they would magically light a beam 200 feet long?

things to ponder eh.

Technically you and Granger are both are right...but also wrong in application, as it applies to the OP issues.

All things equal...comparing a single 800w lamp against 2 400w lamps--total radiance/illumination is 800 watts. But comparing PAR, and PAR watts per square feet, the closer the lamp is--the greater the PAR factor. In this instance, the pair of 400w will be closer to the plant and the calculated PAR will be greater than it will be with a single 800w lamp.

Number of reasons why but the easiest to understand is to compare indirect vs direct light. It is a fact that there will be more bouncing/reflection with the pair of lamps (side by side) than from a single lamp...sometimes the reflection factor can be as great as a 15% bonus.

Another reason is distance and diminishing rate of intensity...it is linear and quite predictive.

 

[Euphoriaholic]

I faced the same situation trying to cover a 6 x 3 area in a part of a larger room.
I went back and forth between the 2 x 400 and 1 x 600.
I liked the 600 because of more density down the plant. (More penetration power).
I liked the 2 x 400 because it covered more area than the 1 x 600.
I get a bigger yield with the 2 x 400.
I get more density per plant with the 600.
I went with the 2 x 400. The bigger yield sold me.

I am about to get a Adjusta-wing reflector in 1000 w to cover the 3 x 6 area. This wiil be perfect for the area if the heat can be managed.

And to answer your question the 2 x 400 does not have the same penetration power as the
1 x 600w. The 2 x 400w is not a 1 x 800w bulb.
The 600w with the radiant hood covers a 3x4 area at most. It was not capable of covering a 3 x 6 area.

 

[EclipseFour20]

Density can be managed...no larf rule here. But as to "cola weight", the bigger the light--the bigger the cola size. Now, as to grams per sq/foot, grams per watt, grams per plant, etc--maximum light coverage is key. Which means it should be most important to reduce the amount of: shadowing, bouncing, photomapping, indirect light, etc.

Tricks like rotating plants, light movers, etc are useful tools to overcome this problem. Compared to a single "sun" that never moves, having multiple lights with a lower intensity can increase the amount of light that penetrates the canopy covering a large sized area.

There...phew, I put words like: "penetration", "increase", and "lower intensity" in the same sentence with ZERO SEXUAL CONNOTATIONS....lol.

BTW, there really is no single "right" or "wrong" way of growing/cultivating....but there are many "different" ways--some happen to "better" than others.

 

[Smelly_Cheese]

I use a 1000k on a light rail in a 4 x 6 area. only move it about 18 inches back and forth for shading. It will cost bout the same but much less in electric and you can grow them tall. I think it would out produce 2 400s and maybe even the 2 600s if you grow them taller as long as height is not the issue

 

[dank.frank]

Eclipse - everyone gets what you are saying...but again, you are talking about ideal distance from the canopy in order to maximize the output of ANY given bulb...My question to you wasn't how do you calculate wpsf - but how does the graph you posted answer the original question being asked by the OP. The correct answer is - it didn't.

It's really moot when the original question is not "how far should I keep my light from the tops of my plants if I use a 400w or a 600w"... which had that been the question...what you provided was extremely useful - and in the long run it does tell him how to maximize the potential penetration of which ever bulb(s) he decides to go with...Sure it's all relative - if you just want to have a conversation about properly lighting a grow room.

What you posted in your last post is pretty much exactly what I posted in my previous post, as far as coverage area of the bulbs...only I lean on the side of providing "too much" light vs just enough - and then compensate by ensuring there is enough nutrition to deal with the heightened metabolic rates that occur under high intensity lighting...

------

I'll never understand why people ask a question and then get direct answers...and then want to insist their preconceived notion is correct - in reference to the original poster....

I think the analogy of the flashlight by Ranger was PERFECT - and I was thinking of the exact same thing in general - however, couldn't word it right so left it alone.

I still think 2 x 600 is the BEST lighting option for his area...if he wanted to be technical. But if it was between 1 x 600 or 2 x 400 - the 2 x 400 is obviously the better choice...

Unless he wanted to put the 600 on a light mover...and then that is another can of worms - in which my experience tells me steady, constant, even light over the canopy is better than a mover - so I'd still say 2 x 400...especially once you consider the over lap in the center provided by running multiple lights.

Anyway...



dank.Frank

 

[Granger2]

Yes, Ranger. I will withdraw from this and go "ponder." I do still contend that a mythical 800w would penetrate farther over a smaller area than 2 well spaced 400s. The wild card in all this is that you can hang lower wattage bulbs closer to canopy. -granger

 

[EclipseFour20]

Eclipse - everyone gets what you are saying...but again, you are talking about ideal distance from the canopy in order to maximize the output of ANY given bulb...My question to you wasn't how do you calculate wpsf - but how does the graph you posted answer the original question being asked by the OP. The correct answer is - it didn't.

It's really moot when the original question is not "how far should I keep my light from the tops of my plants if I use a 400w or a 600w"... which had that been the question...what you provided was extremely useful - and in the long run it does tell him how to maximize the potential penetration of which ever bulb(s) he decides to go with...Sure it's all relative - if you just want to have a conversation about properly lighting a grow room.

What you posted in your last post is pretty much exactly what I posted in my previous post, as far as coverage area of the bulbs...only I lean on the side of providing "too much" light vs just enough - and then compensate by ensuring there is enough nutrition to deal with the heightened metabolic rates that occur under high intensity lighting...
...

Frank, the amount of light is one thing, but what would be "most efficient" is another--hence my injection of PAR.

If one starts with "how many watts do I need to equate 50 watts per sq foot", that answer gives you a starting point--but not the answer to what size is best.

With a starting point at hand, the quest now is to maximize PAR...how close can you go? The graph I posted tells a tale and I suggest we extrapolate from the distances where PAR is between 50-150% (our operating range).

Now lets solve the riddle....

The OP has space of 1.6m x 1m (or for us Yanks...5.25' x 3.25') or about 17 sq ft.

17 feet X 50 watts = 853 watts (minimum requirement)
17 feet x 75 watts = 1280 watts (good number to have)
17 feet x 100 watts = 1700 watts (maximum amount)

Two 400 watts lamps will not work (less than 50 watts/sq ft), so that means the available options are:
1 1000
1 400 + 1 600
2 600
1 600 + 1 1000

Agreed?

Below are distances where PAR is between 50-150% for lamps of various watts (from graph):

1000w: 17-29" (12" penetration zone)
600w: 13-23" (10" penetration zone)
400w: 10-18" (8" penetration zone)

Depending on "how close do you want to go"...or how deep of a "penetration zone" do you want for 50-150% PAR--selecting the appropriate lamps size is now simple.

SOGs probably can get by with 400w (8" penetration)...medium sized plants 600 (10" penetration) and of course trees require the single "sun" with 12" of PAR penetration (starting 17" from the bulb).

Me, I would go with a pair of 600w instead of a single 1000w sun; this is not rocket science Frank.

 

[dank.frank]

LMFAO...really? No kidding. You don't say...

Two 400 would light that area better - but I agree - two 600's are a better choice.

That's how I view it personally...

You aren't going on overkill with 2 x 600 -

I still think 2 x 600w with proper cooling - or if you insist, 2 x 400w.

Just my take on it.

I still think 2 x 600 is the BEST lighting option for his area...if he wanted to be technical. But if it was between 1 x 600 or 2 x 400 - the 2 x 400 is obviously the better choice...

So yeah, glad to know you agree with me.

Again..the question wasn't about having 50 wpsf...It was - should a run a 6'er or two four bangers over said space. I've not said what you stated was wrong - it just does not DIRECTLY answer the question he asked...

The ONLY time you've directly answered the question is here, finally, at the end of your last post:

Me, I would go with a pair of 600w instead of a single 1000w sun;

Except, the original post said nothing about a 1k...so even still.

AGAIN...what you have posted is useful...correct...in a general discussion, broad sense, conversation about lighting...you just never answered the original question...

THAT was my point. Be...well....FRANK. No need to over load a guy that can't realize having 2 x 400 doesn't magically make the flashlight shine 200 ft with a bunch of moot data sets that he has no clue of the terminology or the relevance. Better to just provide the correct answers...

Most people are looking for spoon fed success...feed them.



dank.Frank

 

[EclipseFour20]

Frank, I seldom answer questions (give fish)...rather I give information so others can do it themselves (become fishermen).

Nothing wrong in being charitable and solving everyone's problems for them....we need more people like you! I just roll differently....and believe there is "no single" method/way that is "more correct"; so many paths to the same destination, some easier, some harder, some better, some so-so....

 

[dank.frank]

When ten people post in the thread saying the same thing...and they choose to quote the one person that suggests they might be right...

It doesn't matter if we tell them the sky is blue...they still won't listen...



dank.Frank

 

[packerfan79]

no 2 400s same penetration as 1 400. just twice the footprint