What are the reccomended PAR reading at what height from a 300watt,i dont know how to get high numbers for flowering off a 300watt led?currently in flower and usual par is around 400 to cover 4 autoflowers in flower.
each light is different and you need to contact your lights manufacture to get a PAR or PPFD map with different hang height.
Or use a par meter that's calibrated. Good brand have this information available.
Good Luck!