it does appear to bring budget a few days earlier. I believe Jacks states not to run longer than a week because of the lack of calcium. Seems counter productive because this is near the peak of calcium uptake for the plant.
I always add calcium (CalMag) during the entire grow. Under all these LED lights its virtually a guarantee your gonna see rust spots and calmag deficiency issues. Its the lights and its such a bummer cuz when I grow outside my plants are perfect. I don't even need to add the CalMag outside this only happens with the indoors plants especially the big ones that get root bound and are hungry.
I have the same light HLG Scorpion Diablo its gonna happen with every LED it makes no difference with how much money you spend or what brand. This literally has to do with the physics behind the LED spectrum. Its the Achilles heel of LED lights. Best bet is to add reptile UV bulbs in the corners of your tent. I run 2 of them in my 4x4 and I also have bumped up my CalMag regiment. Even with all of this you can still see it happen with some strains its super annoying. Once again outside the plants explode with just plain water and nothing else. Its definitely the light spectrum.
Distance with most LEDs and especially the Scorpion Diablo is a non-issue. Meaning the lights run so cool that you really don't have to worry about burning your leaves from heat. Notice I said from heat. That is key because you can still shock your plants from the light intensity being too high but from just pure temperature the LEDs are great! It allows you to run them closer to the canopy and just lower the intensity dimmer this way you can save on electricity!
probably around 18 inches but like I said it can be slightly higher or lower because you can adjust it via the dimmer to be perfect. So basically what Im saying is it can still be perfect at 16 inches or probably 25 inches doesn't matter as much so long as the dimmer is set correctly and the light intensity is dialed in.
Full strength should only be utilized during the last few weeks of flower. There is no reason to ever be running it that high unless you are finishing it at the very end of the cycle. That light is crazy powerful and cranking it up that high too soon into your cycle will curl your leaves and put stress on the plants. I have some vintage strains like the 1988 skunk that couldn't handle it even at the finish of flower. Too bright. There are some more modern strains however that can handle 100% power but once again only during the end of flower.
I think 18 inches is pretty safe at 100% without CO2 and provides a nice spread for a 5--1/2 foot wide plant