I was simply going to have a DLI calculator included to convert ppfd to DLI.
I then realized many on here use Lux meters and wanted to add the ability to convert lux to dli.
What I found… I am not sure of…
Apparently… Since lux and ppdf are completely different measurements of light… Lux cannot be accurately converted to dli without accurately calibrating the lux meter to a known ppfd source.
@dbrn32 how do people on here use phones and lux meters without a quantum meter to calibrate the lux meter to?
I came across this info trying to find conversion rates for lux to ppfd, I was surprised to find that:
"It is not possible to convert Lux to PPFD absolutely accurately without providing the light source’s spectral power distribution (SPD). In reality, however, obtaining a light source’s exact SPD is not an easy task for the average grower – it requires expensive spectrometer equipment. "
Lux = is universally used to measure and compare the brightness of visible light.
Ppfd = is referring to the amount of light suitable for active photosynthesis of plants.
" How can I convert light intensity in Lux to micro moles?
The Photosynthetic Photon Flux Density (PPFD), i.e., the photon irradiance, is expressed in moles per square meter and per second (formerly, Einsteins per square meter and per second). There is not a general conversion factor between photon measurements and energy or light measurements for broad band radiation. "
From (screenshot since not sure if I can post the address here)
Correct. This is because the conversion factors are simply found by measuring a light source with eaxh device. The conversion from one wavelength isn’t the same to the rest, so any difference in total light spectrum wouldn’t be linear.
I don’t think trying to convert like this is going to be super accurate without known measurements from both tools on each light spectrum needed to convert.
@dbrn32 That’s what I thought… Thank you for your help.
I had noticed each lux to ppfd converter I found online provided different results.
That’s probably why hlgs website has very specific converters for specific devices.
It’ll save me a bit of coding.
So far the app has:
DLI calculator (hours/day, ppfd) with empty graph/chart for future plotting of data.
VPD calculator (air temp, rh, leaf temp; Celsius/Fahrenheit) charts to be added in future.
Adding:
Daily DLI charting(daily = when calculated its plotted) *current task
Daily VPD charting(dido)
VPD Heatmap chart (link to new page showing vpd heatmap chart for reference which is printable)
Journaling capabilities with pen or keyboard and picture input.
If you want to get a leg up on most apps doing this, program to plot the intensity readings from all over the grow space and create a ppfd average. This is what should be used to calculate dli.
