HLG 550 V2 Vs 1K HPS Single end.

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Mrgoodsusa

Member
Prawn Connery said:
So in the interests of fair play (and because @wietefras won't post this himself), here is a Dialux sim for eight 112cm strips. These are Crees (custom strips) at 48W each. Don't mind the PPFD readings – we're more interested in the light spread.
View attachment 4430936
The first thing you notice is the centre weighting of the light spread. The reason for this is the overlapping light in the middle vs the 80% reflected light from the walls (obviously set at 80% reflectivity in Dialux). The middle of the room gets the most overlapping light, the edges get the least.

And just to prove this isn't a set-up, here is another 4x4 with wall-to-wall boards showing the same light distribution (again, never mind the PPFD figures, look at the distribution curves).
View attachment 4430946

And here we have wall-to-wall strips (or as many as I could fit in Dialux – 28x).
View attachment 4430948

And here we have just a few strips.
View attachment 4430949

The moral of the story is, no matter how many strips or boards you put in a 4x4, the light footprint will always be weighted towards the centre of the light mass. Thus endeth the debate. And apologies for taking this thread off on a tangent.
Click to expand...
Hi is this reason qb have like a big empty space in the middle?
 
wietefras

wietefras

Well-Known Member
Mrgoodsusa said:
Hi is this reason qb have like a big empty space in the middle?
Click to expand...
No it's not. You simply need to spread out light points as uniformly as possible over the grow. So there needs to be some space between the boards to spread it out.

In fact, the QB's are not spread out nearly enough. The HLG550 is only 26"x20". Gavita Pro, Fluence Spydr, Chilled Growcraft, Lumatek Zeus etc etc build fixtures to properly distribute the light and they are 40"x40" (and bigger).

Also, these lights do not create a hot spot in the center. The walls absorb light and therefore create a dark spot near the walls.

See a Gavita light plan for 15 of their lights over a 12.5' x 21' area. Notice there are no hot spots directly under the lights, but there is obviously less light near the walls :
Gavita-Pro-1650e-LED-Layout_RGB.png
 
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