Lighting LUX to Par converters. Which are accurate?

[JayGeeCanuck]

I'm using a lm301b 3000k QBs and was wondering which Lux to Par converter is more accurate.
According to this:
https://horticulturelightinggroup.com/blogs/calculators/converting-lux-to-ppfd


"Calculator For QB 288 V2 3000K"
51000 LUX = 743 PAR.

But if I use this converter:
https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator
For high CRI LED 3000k
51000 LUX = 970umol/s/m2

743 vs 970 is a huge difference. Any ideas as to which one is more accurate?

 

[Bob's Auto's]

You can not mathematically convert Lux to PAR. Lux measures the total light spectrum cumming through and PAR is a piece of that spectrum. The value depends on which light you are using each with their specific light spectrum. Your better off lookin on the interweb for information about your light then trying to calculate it from a Lux value.

 

[Mañ'O'Green]

You can not mathematically convert Lux to PAR. Lux measures the total light spectrum cumming through and PAR is a piece of that spectrum. The value depends on which light you are using each with their specific light spectrum. Your better off lookin on the interweb for information about your light then trying to calculate it from a Lux value.

Correct but reversed Lux is the visible spectrum humans see and is a subset of the PAR spectrum (photosynthetic active radiation) plants see.

 

[JayGeeCanuck]

I know you need to know the type of light. The horticulturelightinggroup link are the same diodes, 3000k spectrum. Likewise, the other link is the same spectrum.

750 is optimal in flower (absent extra c02).

Even adjusting for different spectrum, the par difference isnt 200. Id like to getnan apogee Sensor, but if I can ballpark it with my phone, I can save 100+ dollars.

 

[Bob's Auto's]

If your handy you could try to make one yourself. It still involves buying a PAR sensor, but the guys who made PARduino left an entire wiki with all the information you need to make one.