You can have that light 3 foot up in veg with them little things.. U got to watch what you read because some of these things are wrong, are have other conditions. Like how close and intense to have that light, Those things depend on other factors such as temp(leaf temp) Rh, as well as ppm. Hotter temps(ambient temps) will require you to drop the ppm. Another-words 550 ppm might be all right at 72* but at 82-84, I could experience some over feeding.. The same as in dwc with DO.. At 1.0 lpm 500 ppm might work where at 1.5 lpm you may have to drop it to 375 to 425 ppm because of the increased bio-availability in the rhizophere.
I cant teach you everything in a night, a week, or even a month... Its a journey.