@pdxcanna and I are working on a version of this.
I’m hoping to include multiple sensors (maybe 3) to be placed into grow rooms to measure the light quality at different points.
I am not a grower and am interested to know how you guys would use this technology. If it were more accessible to get more sensors, would you? What kind of features does the program need?
I’d think a mobile meter is best, right? Once you understand how strong the light is, what’s the need for constant monitoring?
I could imagine it being useful to see what the light is doing at any given point constantly vs at a time point. We’re thinking about pursuing both.
If you place one sensor at the bottom of the canopy, one at the top, and one at the middle it could help you zero in on exactly when you should trim off some of the foliage on the plant. (Maybe?)
The consistent placement might help with repeatability but a mobile unit works too.
A situation I saw recently, where the green light was causing reveg, might have been able to be prevented by active monitoring, or at least testing the new bulb
Yeah I heard about what happened down there. Still doesn’t equate to a need for constant monitoring for me. Not that folks won’t want that. Unless it’s accurately controlling lights based on par it doesn’t make sense to me.
I’d like a mobile unit so I can check anything wherever whenever. Especially understanding par value throughout my canopy.
I like meters soni know exactly when I want switch my spectrum, exactly what spectrum I am using etc. Day light color changes hours to hours and day to day. I like to experiment, so I like having sensors. It can be a coat saver for people with consumable bulbs as well. Knowing when you need a new bulb apposed to guessing.
This is more so an argument for having a meter to begin with though right?
Love my apogee by bugbee. Mainly use it for checking the ppfd off the lights and needing to make adjustments to that . Using LEDs it gives quite an accurate reading compared to most.
Yea. A scope just gives you more details. Changes in the spectrum and lighting happen, and they happen more often in a gas bulb, but boards do loose diodes. Ballasts and controllers are known to malfunction causing dimming etc. To me these are all reasons for continued monitoring. One of the easiest way to ruin your flower is to fuck up your light. The sooner you know the better and the human eye isn’t that sensitive to light.
Alot of research is starting to come out about the benefits of out of spectrum ultra violet and far red light. When using these spectra it’s imparative to measure there intensity and range through out the amplified days and seasons.
For Apogee, Full-Spectrum MQ-500 is what you want until ePAR gains wider acceptance by researchers. The Full-Spectrum compares apples to apples in terms of PPFD, and the ePAR compares apples to crab apples. If you buy the Oringal (SQ-110), the best thing you can do, especially for LEDs, would throw it directly into the garbage because its spectral response is garbage.
I know you only asked about Apogee, but I suggest LI-COR’S LI-250Q PAR Package, which inlcudes the LI-190R quantum sensor and LI-250A meter, if this is most important to you:
Apogee’s new quantum sensors are much better than its Original version (which was horrendous for LEDs). But the latest versions still can’t compare with the LI-COR’s, especially the new LI-190R. LI-COR is around 3x the cost of Apogee’s MQ-500. If you get the LI-COR, make sure you follow their recalibration schedule recommendation:
LI-190R quantum sensor: LI-COR LI-190R Quantum Sensor
LI-250A light meter: LI-COR LI-250A Light Meter
Comparison of Quantum Sensors with Different Spectral Sensitivities: https://www.licor.com/documents/oi26ib7eb6wm5y5u9ebv4b3jodm09tf9
jusr re read your first post and your going to struggle getting a “par” meter thats going to do all the different lights justice.
by definition par is 400nm - 700nm so there will be a significant amount of photo active radiation before 400nm and after 700nm that a par meter wont capture, esp on the cmh.
i think apogee’s epar meter is the closest your going to get, at least its capturing far red so usefull for the newer leds with added 730nm’s.
i disagree, why should he wait for wider acceptance by researchers before he buys an epar meter?, if he wants the most accurate reading of photo active radiation falling on his canopy today apogees epar is a good choice.
the li-cor meters are no doubt top quality but they are overkill unless your doing science.
the li-cor li-190r is super acurate between 400-700 but captures nothing out side that so wont be any more rounded in comparing between sodium, cmh and led’s than a sq-500.
i agree that apogee’s sq-110 is junk.
Because the Full-Spectrum MQ-500 is an applies to applies comparison with PPFD. That’s important if he tries to achieve PPFD targets from research papers or other growers or compare his PPFD to others’ PPFD. If the measurement is only for in-house trials and data logging, the ePAR is the logical choice. But, Apogee has a far-red quantum sensor as well…
“Overkill” depends upon your POV. In a commercial grow where accuracy affects ROI, operating costs, and the ability to stay profitable, I would argue it’s not overkill. The same holds for cannaphiles who prefer the best options in their grow toolbox.
The whole point of PAR range quantum sensors is only to measure 400-700 nm 
His stated goal is to compare various lamp technologies, so the quantum sensor spectral response is paramount. LI-COR LI-190R has the best spectral response for quantum sensors on the market.
The MQ-500 will work fine, but it’s a fact the LI-190R is superior for PPFD measurements.
i didnt get that vibe from the op’s first post, but i guess if thats important to him then ok maybe?.
i got the impression that he was having trouble setting the intensity of led’s by eye, more or less any reasonable quality par meter will get you in the ballpark.
are you saying a grow op using a li-cor will out perform ( roi, op costs ect) a grow using apogees sensors?. do you have any data to back that up?.
??? how is that an accurate way to compare lights, its like using a dyno that tops out @ 500bhp to compare 3 different drag cars with 500bhp, 750bhp and 1000bhp, the dynos going to say they are all 500bhp where the cars with 750bhp and 1000bhp will be quicker down the strip.
the best way to compare the different lights would be with a sensor that captures all photo active radiation say from 300nm-800nm.
if you used a sq-500 or the li-cor to set the 3 different lamps all at 1000ppfd, the sodium and the cmh will be under reported (and the led if it has any far red or uv diodes) ie they have photo active radiation outside of 400nm-700nm that is going to contribute to photosynthesis that the meters miss. i cant see how this is an acurate comparision.
say the li-cor measures a light source @1000ppfd and the apogee the same source @1015ppfd do you think that will make any type of meaningful difference in the op’s use case? or any other case outside of scientific research?.
that par definition is old, it was baased on a few plants responses. They were in a lab and ignorant of many things. Like when sunlight filters through a canopy its spectrum changes and different plants will respond in different ways. Evven different parts of the same plant behave differently. Some may want light and will stretch, others may be forest floor dwellers and prefer the filtered spectum. Green is a par
You are probably thinking about YPF or McCree curve. PAR is old (1960s-ish) but not based on (weighted by) plant responses. PAR range is simply the waveband range that is the primary driver of photosynthesis (400-700nm).
Dr. Bugbee co-authored two studies arguing for ePAR to replace PAR only within the last two years: AgriEngineering | Free Full-Text | On the Technical Performance Characteristics of Horticultural Lamps
My point about the LI-COR not being overkill is about a competitive market. Every advantage counts, and for example, measuring PPFD for dimming purposes equates to reduced cost to produce each gram, increased ROI on the fixtures, and reduced operating costs in terms of HVAC.
The only time using a spectroradiometer makes sense is for research or comparing single lamps or LED fixtures before buying many of them at scale. You would not use and do not need a spectroradiometer for daily canopy irradiance measurements. And any home grower gets a ‘good enough’ comparison between different fixtures and lamps by comparing the manufacturers’ SPD charts. Also, a complete spectral analysis is useless if a grower doesn’t know how to analyze those data and what levels and ratios are preferred. There is no need to add complexity for complexity’s sake.
Wavelengths that affect plants are not the same as wavelengths that drive photosynthesis. Sure, they overlap, but we are talking about photosynthetically active wavelengths.
PAR = 400- 700 nm
ePAR = 400-750 nm
You’re missing the apples-to-apples comparison. Those two sensors measure PAR, so you can compare the fixtures using PPFD and compare their PPFD to any other fixtures with reported PPFD (at the same measurement distance). Zero horticultural lighting manufacturers thus far report ePAR irradiance. Zero academic research on cannabis growth thus far has studied umol/m2/s of ePAR instead of, or compared to, PPFD. The amount of photosynthesis from 701-750 is minuscule compared to 400-700, so it’s currently not an essential consideration when comparing fixture output based on photosynthetic yield.
Far-red is important in terms of PPE, plant elongation, and the Emerson effect, but it’s not a critical factor in photosynthesis compared to the PAR range, even though it does drive photosynthesis to a limited degree.
I’m not sure why you’re arguing so passionately
Yes, because you assume they both measure all wavelengths within PAR equally. They do not. We are not discussing the accuracy of the measured wavelengths. We are talking about the relative weight of the measured wavelengths applied by each sensor. The Apogee under-and-overweights the wavelengths it measures to a greater degree than the LI-COR. The Apogee also includes UV-A in its PPFD measurements, further skewing its PPFD measurement. Look at the spectral response curves I posted above.
ralf, just wanted to say its all good coversation. im not trying to push your buttons or anything 
i think its just we are coming at this from different ends of the spectrum, no pun intended.
im a small scale grower on a limited budget that wants the data but without breaking the bank.
your grows and budgets are large and you can afford the best of the best equipment, i would probs do the same if i was in your shoes.
i hear what you are saying, and i know that the li-cor is undoubtedly the more acurate sensor but im saying that the sq-500 is close enough to do all the things you describe.
like i said if you have any data that shows a li-cor equiped facility out performs an apogee equiped facility post it up.
im not suggesting you need a spectrometer for average daily use i was merely pointing out that you can get a functioning spectrometer + a par meter for less cost than some stand alone par meters, are their par readings going to be as acurate as the li-cor, no of course not but it would be acurate enough for a lot of use cases.
i bought a cheap spectrometer because i build my own lights and like to experiment with spectrum, for someone wanting to check general light levels they are completly unnecessary i agree.
as for being able to analyze the data to try and to work out what levels and ratios are prefered is the billion dollar question.
when you say wavelengths that effect plants are not the same as wavelenghts that drive photosynthesis, do you mean wavelengths the effect plant morphology, are not the same as wavelenghts that drive photosynthesis?.
no i get the apples to apples comparison, i know that the amount of photosynthesis generated by photons between 350-400nm and 700-750nm is minuscule but its still there.
in my mind the best sensor to use to compare the different light fixtures would capture every photon of photosytheticly active light.
agree.
we are just conversing. 
i dont asume they measure par equaly, i have looked at those charts before today i know the apogee isnt as acurate at weighting the spectrum as the li-cor im just saying its near enough for most people who dont have the budget for the best of the best,
Definitely not up to PAR
Highly recommend the gossen mavospec base. Pretty expensive but incredibly well featured and accurate. We created our own derating formula based on chlorophyll excitation and another derating further based on photon energy, just export to csv and apply. Also does flicker which is a helpful feature
