How Many LED's To Achieve 1,000 PPFD In 4x6

[Fastarkid]

Greetings kind friends ;-)

I seek an audience with your greatness for help deciding how many of these LED strips to buy (to cram) into this 6x4 foot enclosure that will be lined with something as reflective as Diamond Mylar.

In reference to the attached drawing...

1. If I want all four of those yellow spots inside that enclosure to receive approximately 1,000 PPFD (and the center of the 6x4 floor to be higher than 1,000 PPFD...approximately...very roughly speaking...even 850 to 1,300PPFD at the yellow spots on the floor)
2. when all LED’s are hanging approximately 20 inches above that floor
3. and all LED strips are attached to something that is 3' x 5' (so six inches of space between light panel and walls)
4. using 22” long strips
5. and each strip has 52 LED’s (see attached picture)
6. and each strip is rated at a luminous flux of 1,460 (lm)

• How far apart do the strips need to be?
  • Ten inches like strip #1 and #2
  • or 5 inches like strip #2 and #3
  • or ___ ?
• How many of those LED strips do i need?
• Is it even possible for such a configuration to achieve 1,000 PPFD at the spots highlighted in yellow?

The magenta colored line represents the panel that the LED strips are attached to.
The black line outside of the magenta is the walls of the enclosure which are lined with reflective material similar to Diamond Mylar.
The blue strips are the LED strips.

As you can see, i'm a complete newbie when it comes to PPFD and luminous flux and all that. I'm sure i'll learn more eventually but for now, I'm hoping you can help me with this question, before I learn more, because (due to my learning disability) it will take me a very long years to figure this out without your help. I did read that sticky (pinned) post a few times but it's not sticking and it made me dizzy to read it...frankly I felt a little hopeless after my third reading of it.
Thanks, Dan

 

[Buds Buddy]

Good question for @Nunyabiz . He built his lights & knows about this stuff.

 

[Nunyabiz]

I would go with different strips if you want to get even close to 1000+ PPFD in the corners like that.
Those strips are lacking a lot of density.

The strips I went with have 100 diodes on the same length and they're Samsung LM301B diodes with Cree XP-G3 Photored diodes.

Also to get that high of PPFD in the outer corners you will need to run the lights to within an inch or so of the tent.
My lights I built are 23" X 26" with 8 strips each light.
Thats 800 diodes running at 1400mA which is 325W at full blast @ 2.85umol/j.

I get about 1700 PPFD in a decent size area in the center at 18" and on the outer edge is in the 900s on 3 sides that has just white tile for reflection and the open side without reflection is in the 700s.
I don't usually have it turned up past about 60% in the winter.
Oddly enough I have to turn it up higher in the summer to raise my heat in veg, and raise the light higher.
Because I have to have my AC on.
In winter the AC is usually off or occasionally the heat is on so I can dim down to about 60% and lower the lights to get a fairly even 900 PPFD.

My space is little over 2' wide and exactly 5' long and I built my lights to fit that space exactly in order to get very even coverage wall to wall.

If you built 4 of my lights and spread the bars out just a little to be like 23" x 30" and hung them about an inch or two from the outer walls of your tent then you would have about 8" gap in the center.
That would probably come very close to giving you the 1000PPFD in those areas and probably about 1200+ in the center.

I am not sure you could achieve that with those strips unless you ran them super hot at like 2100mA if they could even handle it.
Ideally you want to run them as cool as possible.

And if you can dim your lights most of the time and still get all the light you need then you have good overhead that you can use as the diodes dim slightly over the years you can just dim a little less.
They will run cooler and more efficient which makes them last longer plus you have spare photons in the tank to keep them at optimum light intensity for years.

 

[Fastarkid]

Is there a way to convert (or at least approximate) the PPFD based on the luminous flux spec?

Sorry, I grabbed the wrong picture. The above strip is not the one I would consider buying.
The picture below is the correct one with;

• 52 LED's
• 22 inches long by 3/4 inch wide
• luminous flux = 1,460 (lm)
• 40 Volt, 14 Watt

Someone said I need 34 to 50 watts per square foot as a rule of thumb but someone different said I should ignore watts and instead look at PPFD. But I don't have the PPFD specs on this strip i only have the luminous flux above.

Very roughly speaking, what might be the PPFD at one meter (or at whatever) of this strip?

 

[Stormblessed]

Yes ppfd is what is important but I think watts gives u a better guesstimate at the ppfd that luminous flux