16k lumens HPS vs. CFL

**ceestyle** · 07-02-2008, 09:28 PM

Originally Posted by moon47usaco

Of what field if i may ask... =]

Should that be lumens per cubic foot/cubic meter... ??

How would you get the square feet of a three dimensional growing area...??

I'll just say I'm in the physical sciences and engineering.

Lumens per square meter is a metric of light intensity (lux), as it's only the area upon which light falls that is relevant.

These general rules of thumb are generally based on a horizontally mounted light or lights with a decent reflector over a number of plants. Of course lumens doesn't by any means describe how you distribute the light over the area, so obviously heuristics depend on your setup. I would imagine that most are made based on a need to distribute HIDs, so are probably best for that use.

**DeweyKox** · 07-02-2008, 11:43 PM

Dam Cee, You so smart! I feel lucky you commented on my Dumb Journal with all my mistakes and trial and error problems. J/K But dam, I just learned allot!

**moon47usaco** · 07-04-2008, 07:50 AM

Originally Posted by ceestyle

I'll just say I'm in the physical sciences and engineering.

Sounds like you work for the government... =] LOL... =]

Lumens per square meter is a metric of light intensity (lux), as it's only the area upon which light falls that is relevant.

That makes more sense thanks... =]

I am already using 6 23W cfl lights in my grow box and was thinking of adding a small watt hps to the flower box... That info is most helpful as i design the locations for the lights... =]

Peace... =]

**nowstopwhining** · 07-07-2008, 06:05 PM

Just stumbled across this link in your signature and it caught my eye.

Very interesting and informative, thanks man

**ceestyle** · 07-07-2008, 06:12 PM

Thanks. Glad you enjoyed it.

**Budda_Luva** · 07-07-2008, 06:53 PM

Originally Posted by ceestyle

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ok from what i was talkin about earlier with the reflector right above the HPS i dont tthink it would allow much light to reach the aluminum above it since the HPS relfector is in the way and cruved reflecting the light diferently than it would from the flat surface of the aluminum foil at the ceiling of ur box and wouldnt some of the from the CFL be blocked from the plants since the HPS reflector is in the way again juss som thoughts i really dont know how light intensity and the relations to reflecting light works but juss some shit that came to my head when i seen ur setup

**ceestyle** · 07-07-2008, 08:10 PM

Originally Posted by n00b_marijuana_grower

ok from what i was talkin about earlier with the reflector right above the HPS i dont tthink it would allow much light to reach the aluminum above it since the HPS relfector is in the way and cruved reflecting the light diferently than it would from the flat surface of the aluminum foil at the ceiling of ur box and wouldnt some of the from the CFL be blocked from the plants since the HPS reflector is in the way again juss som thoughts i really dont know how light intensity and the relations to reflecting light works but juss some shit that came to my head when i seen ur setup

The HPS light will not reach any mylar on the ceiling. It will reach the mylar on the sides, however.

There is a point as you bring the plants closer to the lights at which the aluminum reflector will obstruct some of the CFL light in the center. This is somewhat irrelevant, as you would not put your plants that close to the HPS.

As has been pointed out - first by me and then a couple others - you would ideally want the HPS farther away than the CFLs. It was done the way I have it because the CFLs were in place already. IN addition, a great deal of the CFL light will be reflected by the mylar, making their distance from the canopy less important.

I've been doing some work with reflector simulation, and a vast improvement can be made with a better-shaped reflector for the HPS.

**northerncaligrown** · 07-18-2008, 11:06 AM

interesting grow man! i need some more space and experience before i try some shit like that~! how much did u yield off the two?

**ceestyle** · 07-18-2008, 11:10 AM

It was at about 3 after I had been smoking on it for about a month and it was obviously well-cured. It was also probably two weeks premature, so I imagine I could have had 5 or more had I been able to let it get nice and ripe.

**techhead420** · 07-18-2008, 12:46 PM

Respect out for doing the light mapping. I like to see this sort of empricism.

Lumens is kind out a poor unit of measurement for plant lighting. A pure red light source (say 650nm) is going to have a much lower lumens rating than a green light source (say 555nm) even though the actual photon flux density might be the same. The higher lumen green light in this case is going to have lower photosynthetic activity than the red light. This spectral distribution is my only critique of the testing.

I use micro Einsteins or micro moles (uMol) whenever I can for this reason but you need to know the conversion varaible between foot candles or Lux and uMol with different light sources. It does give a more accurate unit of measurement for the total amount of photosynthetic activity.

Foot candles