cause and effect...I am under 600w Leds.....10 out of 22 are like so....
Sorry guys, hollow stems are usually a sign of low boron ratio vs nitrogen. Maybe try fertigating one consistently with B at .5-1 ppm and one without then compare. And yes be ready for Ca uptake to increase (add some, but not from 'cal-mag' which is more CaNO3). A Ca+B foliar might work faster for remedial use.