how far to put my 600w

So i got a 600w dual arc for veg it was at 75% plants loving it even they got some trouble at the beggining now they are back on track green and healthy my question is if i put 600w at 15 inches away with 75 F° would it be ok? It doewnt have a glass or anything just the vent between canopy and light im growing lemon haze and some free freebies btw this is my second grow

Sounds reasonable to me put it there and you'll know if it's too close real soon.

bullwinkels right, place your hand over the top of the plant and if it starts getting hot then its prolly to close.

I think it is too close, at this stage very little light needed, like 150w cfl ideal , so double the distance and readjust when they double in size, in nature they are shaded by other plants, this stimulate roots growth.

so i think ima let go 6 hours at 75% 6 at 100% and then 6 at 75% again to see how they react, if i see faster growing then i raise 100% hours, have some time to kill ... so...

they liking it a lot only 6 hours 600w tho.. but still growing healthy and green hope it stays this way T_T_T