Yields at differant PPFD?

Atulip said:
I've seen between .014 and .015. Close enough accuracy for me.

I just cross checked with tastyled ppfd values and lumens output and it looks pretty close. I got ppfd of 1064 for 2 of these in a m2 using the lumen value.

http://www.tastyled.com/product-p/t3-2100r.htm
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going back thru my notes...I think you should have an extra zero before the Decimal point for your conversion, big difference! so those might not be close at all, just be sure, I can share the conversion math, have to dig it all up, been a while going back...
 
I thought this may be a good thread to direct this question.

Using the sun system apogee par meter what type of ranges for veg should one shoot for in Veg / Bloom?

I've heard and read that a range of (min.)300-700(max.) PPFD for veg, and or (min.) 500-1200(max.) PPFD for bloom.

But i don't know if this translates to the apogee par meter, please excuse my ignorance. Just looking for some clarification.
 
The way to translate spot readings to a true average would be to map out a footprint and weigh each reading by the area it's in, then tabulate the results and divide. Light drop off isn't linear so more readings would make the average more accurate, but if you know what type of emitter/bins you have then you can work it out on paper with less hassle and no meter. Maybe do both to see how accurate your method is compared to the datasheet/QER prediction.
 
Rahz said:
The way to translate spot readings to a true average would be to map out a footprint and weigh each reading by the area it's in, then tabulate the results and divide. Light drop off isn't linear so more readings would make the average more accurate, but if you know what type of emitter/bins you have then you can work it out on paper with less hassle and no meter. Maybe do both to see how accurate your method is compared to the datasheet/QER prediction.
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Ok cool thanks for the much needed info, Im mapping out D/E fixtures, so idk if the same method applies as emitter/bins.
 
BOBBY_G said:
why is the economics at 20K any different than at 1K?

5 year cost of gavita = $500+ 4 bulbs+ some reflectors = $1000
5 year cost of 640W of cob to replace gavita = $1450

annual cost to run the gavita = 4380 hrs x 1.15kW x $0.15= $755
annual cost to run the cobs = 4380 hrs x 0.64kW x $0.15= $420

multiply that x20 if those numbers dont work
figures above do not account for the massive amounts of AC to cool all the additional heat from the HPSs

payback is ~2 years in most cases
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This post is obsolete already with the plethora of $400 200W diy kits on the market now.

and this is a cree analysis. citizen even quicker payback most likely
 
Guess this guy was a liar, he never provided the pictures of his 3 pound harvests or any harvests for that matter.
 
churchhaze said:
You're totally missing the point. Look at the last paragraph of my post. Even if metric is implied, "PFFD" is not a unit so it shouldn't come after the number. You don't drive at "80 speed", you drive at a "speed of 80".

I am not "180 weight", "I weigh 180".

It's poor use of the English language.
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Sorry.. but your examples are completely wrong! weighing 180KG and 180pounds is completely different..

As is driving at 80KM/hr & 80M/hr
 
Rahz said:
They were asking for source data. Here it is: http://www.ncbi.nlm.nih.gov/pubmed/23572895

PDF: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/pdf/12298_2008_Article_27.pdf
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interesting article. the chart was based on performance under a 2 band led (665/470nm). other charts based on natural sunlight show the same results at 1/2 the PPFD of those LEDs with evidence of light stress appearing around 750 ppfd. it would be interesting to find charts developed using HPS or CMH lights. based on limited data it would appear that photo inhibition is driven by violet light while fox tailing seems to be the result of to much red light.
 

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churchhaze said:
Yeah, people in the US don't know how to use the metric system... It's just so hard to figure out. (sarcasm).

@guod ,in the US, almost all science classes use the metric system exclusively. Even most car manufacturers in the US use metric for almost everything now. It seems like you're trying to imply that people in the US are dumb for not abandoning the old standards, but the reality is that most Americans are familiar with both systems while Europeans are only familiar with one. I guess people in europe have a hard time with fractions.
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Not through,
we still use half ant 3 quarter inch water pipes, and some of us 4 by 4 lumper.

Rilla.
 
JorgeGonzales said:
http://www.angelfire.com/cantina/fourtwenty/yor/prodtable.htm

Some oldschool analysis, and surprisingly accurate when you compare to grow journals.

If the chart is accurate, the difference between incremental lighting steps is pretty small, but adding canopy space is very effective. Moving a 400W light from a 2x4 to a 4x4 can nearly double yield with the same electric bill.

Also makes GPW seem even sillier.
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Also,one of the main benefits to led lights,is that they are not single point lights as configured.The way to take advantage of this is to use smaller wattage led lights spread out over the same area.Single point lights have a hotspot in the center and get dimmer near the edges.So instead of 1 light for a 4x4 you can use 2 lights and get a much more even spread than a single hps light.This in effect increases your growing area because the edges now get enough light.This is a huge benefit over hid lighting.Manufacturers could even make boards that cover an area perfectly in light but, for bigger areas,that creates a light that is very large.Picture an led light with more leds near the edges and less in the middle.
 
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