PPFD seems wrong

[KonopCh]

I am running 20x Q Samsung strips for over 3 years now in 4x4 tent. They're LTQB22A, driven with two HLG-240-C1050A drivers. 3000 K, 80 CRI. I've put these two frames together with Randomblame, so they're running at 550 mA each, if I am not wrong, at 184 lumens per watt or 2.6 umol/s.

Right now, it's my first run with photo plants. They're 7-10 days into flowering. I bumped lights to full maximum, 625W at the wall. Checked with cheap lux meter, and we have problem. It's around 41000-45000 lux/lumens (IDK). We divide this by 69. That's around 600-650 PPFD at 20-25 cm from tops. As close as I can get it, it's around 15 cm from tops and getting 47000 lux/lumens (680 PPFD). And if you're growing, you know 15 cm from light is a really close as you can get plants going. So how do you guys get 800-900 PPFD with 30 watts per sq/ft?

So... something wrong with my lights? Dirty, dusty diodes maybe? Clean tent walls? Old tech?

 

[hotrodharley]

Your own words “checked with cheap lux meter” might be a clue.

 

[hotrodharley]

Do you know anyone with a quality meter to check yours against? I would really watch the tops closely at that distance.

 

[welight]

I find the samsung data a little confusing. the datasheet says
3000k 80 CRI is min 168 lpw at a non listed drive current, 187 LPW at 450ma and 231 LPW at 1000ma, this cannot be correct and I assume it must be back to front, any ideas, on that basis its is hard to know what the umols/j would be and to therefore assess your low PPFD reading

 

[WubbaLubbaDubDub]

Might be time to look into a reliable par meter.
I just grabbed a Apogee mq-100 seems to be the cheapest reliable option

 

[LEDTonic - Max]

While sunlight is nowhere near the spectrum you have indoors, you can calibrate your LUXmeter against sunlight with Apogees' calibration tool.
Sunlight is supposed to convert with factor 54.

If your meter is way off in sunlight, there's a good chance it'll be way of indoors too.
Hope this helped. Good luck

 

[mudballs]

Google Play Store, search "Tent Buddy" by Pixel Platforms...best damn phone light meter out there. DLI (daily light intensity) is something i never see anyone talk about and this has that as well as PPFD and can select which light source, MH, HPS, led, etc.

 

[KonopCh]

Yea, I was thinking to run 14/10 with FR/EOD as I have them already mounted and using them at day. That way I can gain 120 hours in 60 days, this means solid 10 days more to bulk up.

 

[LEDTonic - Max]

so they're running at 550 mA each, if I am not wrong, at 184 lumens per watt or 2.6 umol/s.
So how do you guys get 800-900 PPFD with 30 watts per sq/ft?

Our Q7 lamp is using the same diodes and is operating with roughly the same efficacy (2.55 µmol/J).
We have measured it in several different grow spaces that result in different w/sqft.
You can have a look at the PPFD maps on our website to get an idea of what PPFD to expect from different setups. It isn't a bar-style lamp but the diodes still have a decent spread for being a board-style lamp. Might give you an indication of what levels you have in your grow space.

320w 2x4' = 40w/sqft
320w 3x3' = 35.5w/sqft
320w 4x4' = 20w/sqft

 

[HippieDudeRon]

I find the samsung data a little confusing. the datasheet says
3000k 80 CRI is min 168 lpw at a non listed drive current, 187 LPW at 450ma and 231 LPW at 1000ma, this cannot be correct and I assume it must be back to front, any ideas, on that basis its is hard to know what the umols/j would be and to therefore assess your low PPFD reading

Samsung shows the Min, Typ, and Max. That is exactly what their chart shows. Do not think more into it then that.
You are assuming that each set of rows(flux, efficacy, driver current) and dependant on the each other. They are independent sets of data/characteristics.
The max current is 1000ma...that does not mean it matches or corresponds to the max efficacy. Max efficacy and max current have nothing todo with each other. Only thing the chart is saying is that those are the MAX(best it can do) for each.
The current and flux fall in line(column wise) because they are essentially the same information displayed. They are dependent of each other, but that is not what they charts shows, that's just the coincidence that is messing up your comprehension of what is there. The chart shows each set of info(flux, efficacy, drive current) independently. Min, Typ, Max.

 

[HippieDudeRon]

@KonopCh
"Korona" App on the app store for you iPhone. Free is not horrible with the sun setting. If you pay for the more specific SPDs can be a good tool.

 

[cobshopgrow]

dont trust a cheap luxmeter.
it could be several 10% more ppfd you have in real.
best bet would be to check youtube if one with the same model comapred it to a par meter so you get a conversion factor especially for your device.

 

[Dave455]

I am running 20x Q Samsung strips for over 3 years now in 4x4 tent. They're LTQB22A, driven with two HLG-240-C1050A drivers. 3000 K, 80 CRI. I've put these two frames together with Randomblame, so they're running at 550 mA each, if I am not wrong, at 184 lumens per watt or 2.6 umol/s.

Right now, it's my first run with photo plants. They're 7-10 days into flowering. I bumped lights to full maximum, 625W at the wall. Checked with cheap lux meter, and we have problem. It's around 41000-45000 lux/lumens (IDK). We divide this by 69. That's around 600-650 PPFD at 20-25 cm from tops. As close as I can get it, it's around 15 cm from tops and getting 47000 lux/lumens (680 PPFD). And if you're growing, you know 15 cm from light is a really close as you can get plants going. So how do you guys get 800-900 PPFD with 30 watts per sq/ft?

So... something wrong with my lights? Dirty, dusty diodes maybe? Clean tent walls? Old tech?

get a PAR meter

 

[Autofire]

A quantum sensor is the only accurate way to measure plant usable light levels. Throw any other idea out the window.

Don't stress. Good conditions with a good quality spectrum LED should yield about 1.4 gpw

 

[KonopCh]

Okay, thanks guys. Seems that lux meter is not reliable method, but I didn't know that much.

And bigger picture of this "problem"? Can they get dirty over time? (my cloth over the fiter is going from white to black in a year)
Can we clean our strip lights? Or just leave them till they die?

 

[GBAUTO]

I think that Migro did a comparison using a lux meter and his apogee, and if I remember correctly the cheap lux meter he used gave a reasonably accurate measurement when using white leds. I think the example found that 40k lux was equal to 1000ppfd.
I find that my plants start to show signs of stress when the intensity is over 40k lux.

 

[cobshopgrow]

but his evaluated conversion factor works for just his lux meter type.
there are more to find on youtube making the comparsions to other types and of course getting other conversion factors therefore.

 

[hillbill]

@KonopCh
"Korona" App on the app store for you iPhone. Free is not horrible with the sun setting. If you pay for the more specific SPDs can be a good tool.

The CMH and white LED settings give similar readings, sign up for “Pro” version for a month or two and note your readings, do not for get to cancel. I had that version and took notes and canceled. When I change lighting I’ll sign up again. Only readings that seemed unreasonable was Lux. K ratings always within 50 on all light sources. I find the free version helpful even. The paper diffuser is essential. My phone is IPhone 7.

 

[Week4@inCharge]

Might be time to look into a reliable par meter.
I just grabbed a Apogee mq-100 seems to be the cheapest reliable option

How's the MQ100 working out so far? Worth the grab? On the fence wether to buy one or continue with my cheap lux meter. Plants seem to be thriving with me keeping the lights at 18 to 24 inches away at 100% so far. #inflower (50,000 LUx)