PPFD / DLI

This is a good tool to aid you, but don't start with a "DLI" target... your environment and plant determing "max" DLI -- it is relative, so it varies at any single moment in time. Temp,, RH and atmospheric co2 will dicate max DLI a particular plant can handle. Also, that's just a lux meter using a conversion factor... just as a TDS meter doesn't measure PPM even if it gives results in PPM... it is using electrical conductivity then multiplying it by a factor to spit out a guesstimated PPM... which is what is happening here. Your phone's camera absolutely cannot measure photons.. you need a quantum senso for that.. they are expensive. good thing is, under the same light, it is proportional... just expect some variace with a different light... bigger the difference in spectrum, bigger the difference in output math being done. (e.g. more red or blue etc will cause a difference, which is more proof it is simply using lux and converting it) luckily, most the lights nowadays are very similar. A whiter/cooler light might give a more bloated value than a red/warm light, though. So, if you have different equipment, keep separate notes on each until you are certain they both read out the same way on teh "dli" meter. another bad sign -- ppfd is a volume of 1 m^2... 1 measurement can never give you "PPFD" ... they should know better than that. That is a umol/s reading in 1 spot... you average out severage of those over the whole space and you can calculate PPFD.... more measurements (and equally spaced), the more accurate the calculation. and more sophisticated should be considering a volume of space, cause it's about everything the plant can handle, not just the canopy.