Using a LUX meter for PAR readings

**doleritejack** · 10-08-22, 04:13 AM

Hi all,

I got this data after reading a lot of stuff about LED lighting. It's been mentioned before that PAR meters are expensive but LUX meters are comparatively cheap. But by using the conversion figures below you can get pretty accurate PAR numbers by using your LUX meter. A LUX meter simply gives you the light intensity that the human eye would see. Photographers use them all the time. But a PAR meter gives you the light intensity across the whole light spectrum of which the Infra Red and Ultra Violet cant be seen by the human eye. But it also gives us the "light photons per square meter per second" or PPFD. Which means "Photosynthetic Photon Flux Density". Technical? Sure is, but its vital when buying any light source for growing. Some lights pull enormous watts of power from a power socket but the light output from the light can be the wrong spectrum or not even close to converting that power into useful light intensity. i.e a poor quality light would have low PPFD output. Anyway, all this should give enough info to do some research before splashing the cash on LED lights. Some are top quality and some are ,,,,,,well,,,,,rubbish? It all depends on the quality of the LEDs that are used in the making of the LED panel. Again, some are great and some aren't so great. There are even different grades of LED. The best are called “top shelf” and there are other names for the lesser grades.

So, when reading the graphs we can see the different conversion factors that we should use for different makes of LED lights. So get a LUX reading and apply the conversion factor and you get a PAR reading! Simple? Well, yes it is BUT we don't all use those makes of LED panels do we? However, the advice of experts light scientists is that for the purpose of growing stuff just use the averages of what you see on these two graphs and you'll be close enough. Low PAR is not good, high PAR is the duck's guts.