Setting correct light distance using LUX meter?

diggs99

diggs99

Well-Known Member
So i just got this Dr Meter Lux 200,000 lux meter.

I have a rough idea of what the numbers mean and what im aiming for ( thanks @Randomblame )

My questions,

At 75-80% max power about 20" away from tops, i get a reading of 45,174 lux / 70 645umol/s/m2

Is this telling me to lower my lights? If were aiming for 850-950umols/s/m2?
By lowering my lights, will i also be increasing my lux and can then dim accordingly?

Sorry if this seems like dumb questions, still trying to figure all of this technical stuff out.
 
madvillian420

madvillian420

Well-Known Member
Yes. The closer the light, the higher the lux. The spread wont be as wide if you dim too much or hang it too close, though. I have the same meter, make sure you check every inch of your plant, you might find hot spots like i did.
 
diggs99

diggs99

Well-Known Member
madvillian420 said:
no worries. that meter is a useful little tool i use mine all the time
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Ya im liking it so far. I can finally set the lights to proper distance, so thats nice. Its very easy to use lol

Its my first time growing with Leds, im using strips from cutter, They seem like nice bright strips, its nice to finally see some numbers. I think they are gonna be decent. I am running them pretty soft with many strips per fixture. So hopefully i can keep the lights nice and close and achieve the numbers i want and get good coverage and penetration.
 
diggs99

diggs99

Well-Known Member
something dont seem right in the numbers

In order for me to hit 60,000 lux, my lights are maxed out on vo and ip pots and are like 2-3 " from the plants, I remember @whytewidow saying the lights he built for tman and green were insanely bright and were throwing off big numbers. Our lights are very similar but it seems my numbers are much lower.

So im wondering if something is wrong or if im just not looking at this the right way, maybe my lights are only as good as this?
 
Chip Green

Chip Green

Well-Known Member
How does the actual spacing of the strips compare to what Widow measured?
In my experience, with the exact same LUX device, the concentration of LUX will drop drastically as the strip spacing increases.
My original 8x 560mm EB Gen1 racks were on 2x2 squares. I could hit 50K Lux at say, 6"....
Spread that same collection out to 30" and the LUX would be 30K, at 6"....
 
diggs99

diggs99

Well-Known Member
Chip Green said:
How does the actual spacing of the strips compare to what Widow measured?
In my experience, with the exact same LUX device, the concentration of LUX will drop drastically as the strip spacing increases.
My original 8x 560mm EB Gen1 racks were on 2x2 squares. I could hit 50K Lux at say, 6"....
Spread that same collection out to 30" and the LUX would be 30K, at 6"....
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Hey Chip, thanks for answering

Almost identical spacing on our builds

If anything mine are spaced closer.
 
SMT69

SMT69

Well-Known Member
I'm with ya brother, I'm always trying to dial in intensity via my cheap lux meter. I highly suspect its not accurate.

A guy in another post just mentioned he checked his at 40,000 lux against a nice ppfd meter and he was really over 60,000.

I have been seeing similar results over the last 4 grows with these strips, they are much more intense than I thought.



 
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diggs99

diggs99

Well-Known Member
Ya i paid decent money for the meter i bought, its far from top of the line or anything, but it wasnt cheap cheap lol

Im concerned the lights arent putting out the light/power they should be in comparison to WWs builds with the same strips and drivers.

Ive had a few issues since i lit them up, driver problems and then strip connectors, so im a little worried i got something messed up and the lights arent preforming like they should be lol...if thats even possible, i dont even know bro lol
 
SMT69

SMT69

Well-Known Member
How many lux are you getting and at how many watts and how high above... just curious
 
diggs99

diggs99

Well-Known Member
each fixture is 3x4 and each is powered by a 480h-48a driver.

At 2-3" away from tops and both pots maxed out im reading 61,247 both are reading the same.

I was under the impression with this setup i would be dimming lights in order to keep them close. At those numbers i can keep them 2" away and still be well within the 1000/umols/m2 mark
 
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1212ham

Well-Known Member
Sorry diggs, but I think your meter is a lot cheaper on ebay. Not sure, but I think @Randomblame said his meter reads 10% low. I've been tempted to buy the same model you guys have just to compare.

Lot's of variables, reflectivity of the tent walls etc. etc. If you measure within a few inches, the exact distance really affects readings. That, and whether it's directly under a strip or between them. I'll try to get some numbers tomorrow, don't want to rely on memory.
 
radiant Rudy

radiant Rudy

Well-Known Member
Ill put up some lux numbers tomorrow. Take a reading under the sun as well (without clouds, close to noon).

There is a thread here which discusses how to use certain multiplier, dependent upon kelvin, to convert lux to par.

3-25 lux.jpg
 
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diggs99

diggs99

Well-Known Member
1212ham said:
Sorry diggs, but I think your meter is a lot cheaper on ebay. Not sure, but I think @Randomblame said his meter reads 10% low. I've been tempted to buy the same model you guys have just to compare.

Lot's of variables, reflectivity of the tent walls etc. etc. If you measure within a few inches, the exact distance really affects readings. That, and whether it's directly under a strip or between them. I'll try to get some numbers tomorrow, don't want to rely on memory.
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Hey bud, thanks for popping in.

Ya its far from the best and most expensive, but it wasnt as cheap as some lol...the first one i was gonna order was only 22.99

Thats the meter i ended up buying.

https://www.amazon.ca/gp/product/B005A0ETXY/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1


i took readings all over the canopy, there were small fluctuations up and down in certain areas, mostly it was pretty consistant all across the canopy tho.

Maybe im overthinking this too lol, i just remember whytewidow telling me that ill want to keep the lights dimmed and they could be slammed down on top of the plants nice and close.

But as it stands now, the lights are running at max on both pots and only reading 60,000 at 2-3" away. So my newbie led brain thinks something isnt right lol
 
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1212ham

Well-Known Member
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SMT69

SMT69

Well-Known Member
Yea that doesn't sound right I agree man

I'm running 480h driver with 14 strips and get 50,000 lux at 12" above using 300w dimmed (2x4' tent) , our spaces are different but still
 
diggs99

diggs99

Well-Known Member
1212ham said:
I probably overlooked the exchange rate. I have this one. It's anywhere from $27 to $110 Canadian on amazon, $16 US on ebay. Ya gotta be careful buying Chinese stuff on amazon or flebay, it's sold under many names and prices are all over the place.
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i seen that one when i was looking, there were no reviews on the one i looked at, so i went with the dr meter, it had lots of good reviews. Prob just dr meter schills lol

i paid 46.99 cdn for mine.
 
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