ive just noticed due to my intense leds, that when i go below 27 or 25 at max, that my lights need to be dimmed right down as i get purpling tops and dry ripple looking leafes from the stress off the lights intensity,dont go mad if its below 27C.
i prefer above 25C myself but they never do bad as long its clearly above 20 (i seldon to never have a temp below that during day, cant say therefore).
apparently this is the case due to the slowed metabolisum not beign able to process calcium and magnesium not beign metabolised fast enough to deal with the lights,
VPD is the critical component here where the humidity doesnt fall in to the relative space for proper transperiation leading to deficiencys and desease,
with the leaf surface temp reduced underled it seems the important factor is the temp and humidity, as when temps are below 27c with led the plants is now in the sweet zone, they prefere it hotter than hps and atm im colder but i cant increase my Dimmers from 40% without stressing them though it raises temps it doesnt raise them enough to deal with the intensity, i feel the heat needs to be more than what the leds can deliver to make the ramp up of the leds efficent,
like if i used the oil rad to rasie the temps beyond whta the led is cabable of delivering it would widen the gap by increasing the cal and mg metabolisium and allowing for more intensity of light
i am an organic grower so i dont really like adding sprays and things of ca mg especialy when there already there just not being used efficently so adding more would over do the soil and plants with unneeded camg to casue problems again later on lol