# How to increase LED PAR



## fishbone11 (Sep 11, 2014)

If one LED fixture does not have enough of a PAR value at the gravel level, would a second fixture next to the first (side by side) improve the gravel PAR reading? Or, just spread the PAR around farther into the corners.


----------



## AnotherHobby (Mar 5, 2012)

Yes, and yes. 

I did a test a few weeks ago with two Current Satellite + lights and my Hoppy PAR meter. With just 1 light 12" above the meter I measured 31-32 PAR on center. With the meter moved 6" to the front or back I measured 25 PAR. Adding a second Current Satellite + light, with the two of them equally distanced from the edges and each other, I measured 55 PAR in the middle, 50 under each light, and 38 at the far front or back. So that's a little over a 70% increase in PAR, with much better spread.

I would expect similar increases with other brands/models of lights.


----------



## fishbone11 (Sep 11, 2014)

Wow, exactly the info I was looking for.
Many thanks.


----------



## Tshavo (Sep 1, 2014)

I agree with AnotherHobby. More light over the same area = higher light density. 

I would also expect similar increases, but LED manufacturers have the luxury/curse of having to pick which colors to add together to get a certain color temperature. A bulb from one manufacturer may have peaks in the spectrum at say green, blue, and violet, while a bulb from another manufacturer making the same color temperature may have more blue and violet, and maybe a little yellow instead of green.

With a fluorescent bulb the spectrums are more spread out and similar.


----------



## jeffkrol (Jun 5, 2013)

Tshavo said:


> I would also expect similar increases, but LED manufacturers have the luxury/curse of having to pick which colors to add together to get a certain color temperature. A bulb from one manufacturer may have peaks in the spectrum at say green, blue, and violet, while a bulb from another manufacturer making the same color temperature may have more blue and violet, and maybe a little yellow instead of green.
> 
> With a fluorescent bulb the spectrums are more spread out and similar.



Actually it is a but more complicated than that.. and somewhat the opposite..
LED's are pretty "standardized" at blue plus phosphor.. Flour are all over the board w/ spectrum totaling to a specific CCT.. 
6500k LED:









Most 6500k LED's will be pretty close to the same spectrum.. moreso than 6500k fluorescent..

you can see LED's here:
http://www.1023world.net/diy/spectra/


THAT said though, they both suffer from the same "problems"

2 6500K "flour" here:










> Spectrographic analysis of a Lights of America "Sunlight" ~6500°K 14W CFL.













> Spectrographic analysis of a Trisonic "soft white" ~6500°K 9W CFL.


http://ledmuseum.candlepower.us/led/spectra7.htm

Granted most use the same RGB phosphors..


----------



## Tshavo (Sep 1, 2014)

Oh I guess I got that a little backwards didn't I. Whoops. Thank you for the correction.


----------

