Did you see the Migro video where Shane puts his apogee meter beside one of the cheaper Lux meters? He does so with a few different lights, to show the conversion math between the meters is steady. I trust he would of also corrected the agogee meters reading, as they too are not good at reading LEDs but have an equally consistent conversion factor. They are all on the apogee site, showing they can be as much as 50% inaccurate. A fact that seems to escape people on youtube doing light tests. I have not seen a single one of them correct their readings appropriately. Making my use of Lux meter more accurate than their use of a fancy meter costing many times more.
If your maths is on point, it's worth watching. Essentially at 600ppfd the meter he used said 25,000 Lux. I have put that meter under lights where it said 25,000 Lux and then swapped it for the cheapest meter we can all get. The 10$ grey one with 4 buttons. It said 20,000 Lux under the 3000K+660 light I used.
Yes folks.. I did the work so you don't have to. The Cheap meter say 20,000 at 600ppfd.
It's actually linear to around 800ppdf. After which, you are watching your power consumption meters again. I plotted the lot.
HLG offer a conversion like 40,000 Lux is 600ppfd but I dunno what meter they used.
One take away from this, is that all lux meters don't work the same unless under sunlight.
Tech: Most meters are centered on green, but the bandwidth differs. So they are measuring the green light quota. With different amounts of rejection to other colours. So meters don't watch green though, they are centered on red. I'm guess the
HLG meter measured red (40,000). The two I used measured green (20,000 + 25,000) but with different out of band rejection.
I'm really all about the kit, not the plants.
Edit: God damn it, I missed the point.
Epsom salt is 10% Mg and yes I weigh it. Tea spoons and gallons are not a recognised index system, and don't suit 10 base maths. It's a handicap. I want to tell you ppm of 2g or a teaspoon, but it's lost in the non scientific nature of these measuring systems. It's just hit and hope.
2g is real. Put that in 10L and you have a 20ppm solution. Look at the symmetry of the numbers there. Now try a teaspoon in a gallon. It's not even approachable. How many grams on your teaspoon, because you have to use Metric. Then who's gallon, as it's not an Si unit. So it can be turned to Liters. So you can do the ppm. Which is metric.
Non of us are so old that we didn't learn modern maths at school. So using antiquated measurements shows a desire to turn your back on growing science. To shove your hands in your pockets, then try and pick your nose with a street sign.
Meh!
You found one of my biggest gripes