Light height / Lux levels help needed

S

Scrogfather

420 Member
Hey everyone Scrogfather here

Was just wanting someone who could possibly advise me on lux levels as I'm getting a little bit of light bleach on my current grow (2 weeks into flower) so I decided to buy a lux meter to try and be a little more accurate while adjusting the lighting and with the lights at their current height I was getting lux levels of around 150,000 lux so i raised my lights to the top of the tent and was still getting readings of 80,000 lux is this too much? Does it sound like I'm measuring the lux right? (Measuring at highest point of canopy) and is lux something to go by as the maximums I've read are about 75,000 while in flower?


Basic stats for grow
•Tent = 6.5ft x 6.5ft/ 42 sq.ft
•lights = 4 X 600 watt air cooled hps / Total 2400 watts
•Total watts per sq.ft = 57 ish (perfect according to most websites on the net?)
•8 pot rdwc system
•8 inch exhaust / 6 inch intake for tent
•8 inch exhaust / 6 inch intake for all 4 air cooled hoods
•12 inch occilating fan for even temps within the whole tent (not pointed directly at canopy)
•dynamic frequency fan controller
•Temps = 75.2°f lights on & 69.8°f lights off
•Humidity = 45-50% lights on and 50-55% lights off
• Nutes in Rdwc are currently at Ec 1.5 and stable
• Top up tank is at 100% strength with a whole system change every 7 days including Rdwc
•nutrient temperature is 64.4°f consistently with the use of a chiller and heater
•Strain = Photo period Glueberry OG

Hope someone can help

Peace
 

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Lux wont tell you much. It may give you a very wide ranging idea but par is what you are after. I have both a quantum par meter and a lux meter. I'll go get you a lux reading from my room right now since my grow lights are on. I dont worry about lux but I test par readings and I know I'm at 1100 par at the tops so whatever my lux reading is will give you a very wide range guess I suppose. 1100 par at the tops never light bleach anything but is about the max par level without it being wasteful. If I ran co2 then I would run higher par. I'll be back with a few lux readings.
 
I'm having a rough time even finding my lux meter. That should tell ya something lol. Still looking
 
On my particular setup with my cob lights I'm getting 1100+ par at the canopy. You dont want anymore than about 1100 par unless you also run co2. My Lux meter says 76,000 lux. Your millage will vary for certain but that may give you a good guess. My lights would be about the 3500k-4000k in low CRI color. I would shoot for about 75,000 if I were you.
 

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Stunned said:
correct me if I'm wrong
there's no way to convert lux to par?
I might shell out to buy a decent lux meter
and I would love to own a Quantum par meter, but I can't justify spending 500 on it
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You can justify it 2 ways. Either missing out on yield every grow fue to insufficient lighting, or too much light that light burns your crops. Pays for itself quickly when you know exactly how much par every corner of your area is getting. That being said, yes, you can convert it like I just did for you and is why I mentioned my lights color spectrum and CRI but again, that conversion will not be very accurate unless you know EXACTLY EVERYTHING about your lights in very high detail.
 
Stunned said:
correct me if I'm wrong
there's no way to convert lux to par?
I might shell out to buy a decent lux meter
and I would love to own a Quantum par meter, but I can't justify spending 500 on it
Click to expand...
man, pretty much i posted about my lux/par conversion with pics, pretty sure you flamed me for my findings on it,lol.
 
If I were someone like LEDGardener or I was constantly switching out lighting systems it would make more sense for me.
But I know I have a great lighting system, so it would be more of a curiosity thing.
I suppose it would be nice to see PAR values at different heights because I do raise and lower quite a bit
But if I had lights dialed in then I'm sure the meter would just gather dust once I had the values I wanted
I dunno... maybe if I'm flush closer to tax time haha
 
i had a Hydrofarm PAR meter, and a Lux meter, and calibrated the lux meter to read as PAR reading. it is dead on, and then sent the PAR meter back for refund after calibrating my lux meter.
 
Mayne said:
i had a Hydrofarm PAR meter, and a Lux meter, and calibrated the lux meter to read as PAR reading. it is dead on, and then sent the PAR meter back for refund after calibrating my lux meter.
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However, it will only be calibrated for that specific light. As I'm sure you already know. Any difference in spectrum will throw it off. But you're right, if your room stays the same, once you have calibrated for that setup you should be good. Good idea actually.
 
This was using the Perfect Sun mini. I also checked my COB set-up, and it was still, right on the money. Used a conversion of 65. Lux divided by 65, it gets you close enough to save $126-$500 in the long run.
 
also, i do want to add, its best to add 10% to the value. That is the curve of the $500 model PAR meter. The hydrofarm/Apogee ratio. Still, no big deal, I just cant justify paying all that money for the PAR meter, rather use it for CO2 meter or something like that.
 
SmokeSara said:
Check PAR data, you need around 300umol/s for veg and around 700~800 for flowering. :green_heart:
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Those are about minimum numbers. I like to use those numbers for the bottom branches.
 
You can convert lux to par but there are only set values available for a handful of light sources, led grow lights not included. (The red and blue LEDs throw the calculations off.) I wish I could afford any sort of meter to measure my lights. The sensor on my phone maxes out at 27.4klux and my canopy has a distinct hot spot in the middle

Daylight is 100k lux as a reference.
 
Cheers for the replys everyone, so I found a website that actually converts lux to umoles/m2/s and it says that the par for a hps at 80,000 lux has a par value of 960

Which is still confusing as some people hang their 600watts at about 12 inches and mine are currently sat as high as I can get them at 33 inches above canopy

Will the overlap from the lights be that substantial in increasing the lux/par?

Just done another lux reading and I'm still getting reading of 136,000 lux which would be a par of around 1632. So confused as I thought ideal range for a 600w was 18-20 inches away!
 

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