Lux vs Light Distance

Forgot to ask, what do you use to measure your light? I was using an app on the phone today and I know some would maybe frown on that but so far compared to calibrated equipment I use for work, the apps on the phone are surprisingly accurate.

Fake it til you make it is how I live my life lol

Well as long as the conditions are right the light can get really close. When you play with light intensity and height the possibilities are endless. Charts are good but I’m a stickler for perfection or achieving the best of my abilities. I have the light meter. Takes all the guess work out. I set my height up to what I want. Put the meter in few places a canopy height and adjust my intensity to my desired PPFD and boom. Set it and forget it. Lol. Until I make an other height adjustment and then I readjust my intensity. The beauty about growing is that there are some fundamental rules to follow and the rest is all made up. I fake it until I make it 🤣

No worries Papa_T I like learning new stuff and I science for a living so going down a new rabbit hole is always exciting! Mr Stinky, I think the one 250w may be a gross overstatement because someone gave the light to me and that was my best guess from similar products online. The 600w I did buy, but maybe it's just junk because it loses intensity at a pretty short distance. The more I research it the more convinced I am that these distances they recommend are completely arbitrary unless a lot of other factors are taken into account.

Thats right @Papa_T Your diary says you have 850w LED - if that is correct then you would be melting your plants at 15" if at 100% power - what kind if light are you using? There should be a ppfd map, if that is accurate, for a veging and flowering plant you should be aiming to deliver about 550ppfd 20 hours a day or 620ppfd 18 hours a day to be delivering a DLI of approx 40 which is beneficial to your yields and about the top end for an auto and 700-900ppfd for photos (the math is proportional).

Yeah you can move your light closer for sure. And monitor the plants for the next day or two and if it starts affecting them negatively move the light back a bit. If they’re happy with the change closer then continue on with the changes you’ve made.

Yeah you can do the nerd math but it is not real world accurate. There’s a video on YouTube at the Apogee channel. Bruce Bugby is a professor at a university and he demonstrates how the math can get you to a ball park but as you change conditions the formula can be plus or minus 20%.

No you’re right I agree. I may be a bit harsh towards it. Lux is at least a value you can use. I however couldn’t answer your question because LUX isn’t a measurement I follow. I however deal with PPFD. I’m sorry if I came off a little harsh. It just makes more sense in my opinion to follow PAR or PPFD.

I did some research from what you said, which is good information but I still don't think lux is completely worthless. You can do some basic nerd math and convert between visible light and the photons your plant can use. Now, back to square one, if I still think the PPFD is low can I move the light closer?

Papa_t if you re-read what I said, I agreed with you.

So why not use the proper measurement? I mean I don’t go to the gas station a buy 100 kgs of fuel do I? Anyway you do you!!

Lux is universally used to measure and compare the brightness of visible light for us to see, PPFD and PAR describes the actually usable light for photosynthesis in plants.

Stop dealing in light measurements that mean nothing to plants. PPFD is what translates to proper light spectrum for a plant. Sorry but LUX is junk.

You can depending on your light. But I would move it closer a little at a time. Watch for stress. If it starts bleaching the leaves or taco the leaves move farther away.