I use this to convert. But let's all remember here.
All of these meters don't mean shit in the grand scheme of things for an individuals grow. They are needed for a ballpark for new growers. Professionals should be using top of the line for record purposes that are calibrated professionally using known standards by certified equipment. Let me explain why.
The lux, FC , par, quantum meters are all specific to basically the spectrum of light they measure and conversions can be done.
But how accurate it will be is dependent on the accuracy of the meter used to read and the calculations used to do so.
Factors that affect it.
1.The meter quality used and if calibrated to accurately measure the unit used.
Phones can be way off depending on the make and model.... like way off and should be calibrated to atleast an actual meter for the unti before use.
2. The proper conversion of the using measured to the units desired.
This is absolutely huge.. like mind blowingly huge.
Say lux on a blurple 30k lux on a blurple is around 2700 ppfd. When comparing to a 4000k high CRI at the same lux is around 500ppfd. Thus is because lux measure primarily green light.
Add to that par, lux, FC do not measure UV, or IR. So home growers meters don't matter and a ballpark is good enough because we have to read the plants anyways.
So why bother ????
Well because you want to collect information to have a reference point. You start the plants at 10 lux by your meter (that's accurate or even not accurate) and you now have a known measurement no matter it's accuracy that can be used adjust light intensity.
It doesn't matter if your reading 200ppf or 400ppfd and numbers do not dictate what a plant can handle... only the plant does.
Then by using the same measuring equipment you take notes and learn at what stages what numbers are ideal to maximize the light provided.
It also gives you an idea of what light intensity you want to be at in flower after a couple weeks of slowly increasing based on the change of hrs.
Eg. Going from 18/6 to 12/12 after the first couple weeks you will want to have reached 1/3 more than you did in under 18/6 to provide the same DLI because you have reduced your light duration by 1/3 you want to increase the intensity by the same to roughly get tk where you know they will be maxed.
It's a tool and not a rule is what I'm saying. As long as you get a measurement that you can adjust and record to make adjustments the unit of measurement doesn't matter at a home grower level.
Now when you start speaking of manipulations with UV, far red and IR then that's a ballgame you want to have a quantum meter so you are truly able to read what's coming out.
