If you are running a 600w a little over a foot away...you need more than a oscillating fan...you need a small fan dedicated to the area between the light and the canopy. to blow away radiant heat!

It sounds like heatstress to me...curling leaves are usually attributed to a ph imbalance. ph for hydro MMJ, veggies differ. for MMJ ph at 5.4-5.9...experts call 5.8 optimum, but in flower the PHd's from Advanced Nutrients have found the more acidic/lower ph settings better.

hope this helps. Remember, every time you try something different, you stress the plants...stress = more males /hermies.

goodluck bro. lw

perlite in what?

What kind of system...watering times you tried?

all very important ...help us, help you, by giving us a bigger picture.