You already know, what the good LED's do buddy.
I have one single 300w in a 4x4. SC is about 32" from PLC CX300.
I have yet to have a plant handle the recommended 18" during flower. My Beary Whites are @24" and that's pushing it.
Even at this distance, I need to up Calmag to 4ml/L once flowering starts. Is that absurd? Is anyone needing that much?