Why can’t you just use the conversion factor without the tape and hole?
Led design help
- Thread starter SamWE19
- Start date
InTheValley
Well-Known Member
You can, thats up to you. I do it this way so i dont have to crunch the numbers, and can move my meter around and read it just like a PAR meter would. OCD gets the best of me sometimes,lol..
So all your doing really is dividing lux by 65... that’s what I’ve done with my lux readings at the beginning of this thread but they turn out far from what I wanted so I’m hoping that dividing by 65 isn’t right or lux meters are often cheap shit that dont work accurately
InTheValley
Well-Known Member
what lux meter are you using? The iphone ones are garbage. The Lux meter i use is the best from what ive.
Your using 3000K? You want to divide by 60
3500k half cobs 90 cri half 80 cri
The lux meter is a decent branded one from amazon worked out about 35 usd
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Actually just double checked they are 3000k half of them 90 cri half 80 cri
InTheValley
Well-Known Member
the orange one,? dr. meter LX1330b is the one i use.
use the 60 conversion, you should get a great idea of the PAR.
nah it’s called urceri handheld digital light meter.
Dividing my numbers by 60 still seems quite low it gets me 1133 par 20cm from cobs.
When I planned to build this I was expecting over 1500 ppfd at 20cm from cobs
Now that I read the description again though for this lux meter wtf does this mean
- High accuracy of ±3% rdg ± 8 dgts (10,000 Lux)
InTheValley
Well-Known Member
no clue man, but 1500 is to much, 800 is sweet spot with LEDs,
Rahz
Well-Known Member
I looked up your meter. +-4% accuracy when measuring a source over 10,000 lux. If it's calibrated correctly I would expect readings of around 90,000 if the divider of 60 is correct, at 12" in the center of the grid. Where from were you taking measurements?
The system I was pulling 3.5 gppw, was 850 PPFD and 60g/sqft in hydro so even if the meter is correct you should blow past 1z per foot.
But I don't see how you are getting readings of 61K at 12". One lamp I currently run, it's 44w per foot, at 44% efficiency. Estimated PPFD is 1007. I get readings of +1150 in the middle of the grid, 30cm down.
If the lamps are operating as intended you should be seeing lux readings that translate to well over 1133 PPFD in the middle. If you're getting 61K readings closer to the edge that might make sense.
The system I was pulling 3.5 gppw, was 850 PPFD and 60g/sqft in hydro so even if the meter is correct you should blow past 1z per foot.
But I don't see how you are getting readings of 61K at 12". One lamp I currently run, it's 44w per foot, at 44% efficiency. Estimated PPFD is 1007. I get readings of +1150 in the middle of the grid, 30cm down.
If the lamps are operating as intended you should be seeing lux readings that translate to well over 1133 PPFD in the middle. If you're getting 61K readings closer to the edge that might make sense.
800 without co2 1500 with co2 is the high end I believe?
Wanted 1500 at 20cm but plants wouldn’t be at 20cm
The 20cm reading was 20cm away from the middle set of cobs I’ll do another reading tomorrow and see if there’s any change.
Due to me having 4 cobs per square foot could it be that light from the other cobs won’t merge until the sensor is more than 20cm Away?
120 degree beam angle how far would light have to travel outward before it reaches 30cm to the left or right?
Another thing, they do seem to put off a shit ton of heat. When I was in there with the lux meter yesterday I had sweat dripping off my forehead after being in there 5 minutes.
My AC would usually take care of it but I didn’t have the ac on for the tests. I assume it’s normal for there to be an insane amount of heat from this amount of wattage even for LEDS? or could I have messed up with heat sink or thermal compound connections or something that could cause a drop in efficiency?
Also I finally found a supplier of a par meter in this country!
What’s your opinion on the seneye reef? Not exactly made for our purpose but how accurate is it for our needs?
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Rahz
Well-Known Member
I'm most interested in the 30cm readings and at 4 cobs per foot you should get really good mixing at that distance. You do have some variance in cob spacing between the sinks so I would try moving up/down from the middle and seeing what kind of spread you get, but if your readings at 30cm were 61,000 I wouldn't expect it to change much.
Someone more qualified than me to talk about 1212s would be @CobKits so maybe he can provide some perspective, but at risk of repeating myself, in the middle of that size grid, and 60w per foot, you should be reading over 1500 at a foot away. I've done the estimates and taken the measurements on more than one system and the readings always average out pretty close to the estimate and center readings are always higher than the estimate.
I haven't mentioned hooking things up to a watt meter because I assume you have done due diligence on the design, but checking watts from the wall would be a way to make sure the cobs are actually pulling 15w each. You should be pulling about 16w actual for each cob.
Someone more qualified than me to talk about 1212s would be @CobKits so maybe he can provide some perspective, but at risk of repeating myself, in the middle of that size grid, and 60w per foot, you should be reading over 1500 at a foot away. I've done the estimates and taken the measurements on more than one system and the readings always average out pretty close to the estimate and center readings are always higher than the estimate.
I haven't mentioned hooking things up to a watt meter because I assume you have done due diligence on the design, but checking watts from the wall would be a way to make sure the cobs are actually pulling 15w each. You should be pulling about 16w actual for each cob.
Rahz
Well-Known Member
Regardless of what your lux meters says you have about 2400 par watts in play. It's just a matter of figuring out how to get it where you want it and worrying less about what the meter says.
I suspect the cobs clusters are 12" center to center in a roughly 4" square so 40" vertical light 16 inches "above" a canopy. If this is about right, I would choose 45 degree angled reflectors starting 4 inches from the top/bottom cob, extending an additional 12" height/depth terminating into a reflective horizontal plane which intersects at pot level or as close to the pot level as possible. This provides 6' of vertical height and average PPFD of 1000. That is the best possible situation you can find yourself in. You can bring in the pot shelves to shorten the ideal vertical distance a few inches but I don't think it would improve yield or quality. You can restrict the growth zone to 4' vertical with horizontal "walls" and also move the shelves in as much as possible and get the highest possible readings in an 80 sq/ft area. I would much rather have the 1000 PPFD in 120 sq/ft space, jamming the CO2, and expecting yields of at least 60g/sqft in a 120 sq/ft area.
Yeah I’ve used a watt meter and the wattage does equal 15-16w per cob.
I’ll take your advice raz and leave the system where it is and I’ll build the reflectors as suggested above. As soon as I get my hands on some decent hydro nutes I’ll get a run going
Your spot on with your assumptions on the spacing btw. I also have them mounted into a wooden frame built out of 2 x4s I then have a huge industrial 880m3/h axial fans mounted below each stack blowing air up over the cobs and it circulates air in the room perfectly too
I ran the lux numbers again and got the same results so either the conversion factor of 60 is way off for these cobs or the lux meter is junk.
I found a supplier of the apogee sq 500 who will import it here but it would cost me 630 usd. Don’t think it’s worth that price maybe if I do a grow and i don’t get the yields and outcome I’m looking for
I’ll take your advice raz and leave the system where it is and I’ll build the reflectors as suggested above. As soon as I get my hands on some decent hydro nutes I’ll get a run going
Your spot on with your assumptions on the spacing btw. I also have them mounted into a wooden frame built out of 2 x4s I then have a huge industrial 880m3/h axial fans mounted below each stack blowing air up over the cobs and it circulates air in the room perfectly too
I ran the lux numbers again and got the same results so either the conversion factor of 60 is way off for these cobs or the lux meter is junk.
I found a supplier of the apogee sq 500 who will import it here but it would cost me 630 usd. Don’t think it’s worth that price maybe if I do a grow and i don’t get the yields and outcome I’m looking for
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Screw it ive bit the bullet and bought it. Estimated delivery 15-20 days from now. I see this model is the one growmau5 uses in his video when he tests the crees. He does have lenses on them though I don’t know if that gives better depth to the light but I’ll know the answer in 20 days!
InTheValley
Well-Known Member
dang man, thats alot of cash for some numbers, but heck, if you can whyyyyy not, lol,, intested to see the results now, ..
Got any ideas how I can map out a grid in the air vertically to measure par with this meter?
Easy when your hanging lights horizontally you can just move them closer and put a piece of paper on the floor
InTheValley
Well-Known Member
probably the same as you would horizontal, but using a stick to make sure your getting the same consistent distance while mapping it out. and use sunglasses or eye protection. probably will take 2 people to do it. but keep in mind that you wont have the floor surface to reflect light, so your reading will be directly and exclusively COB light values. which isnt a bad thing as it will be a definite value of the light.
Humple
Well-Known Member
From what source did you get the factor of 60? I've seen factors of 67, 68, and 69 tossed around, but this is the first time I've seen someone suggest 60.