heat stress bull crap your frying them with 2 much nutes the main thing that makes up the nitrogen in those urea nitrogen which is a very hot nitrogen source meaning it will burn ur plants right up if you use it like they recomend. also for the price that stuff you got you could of bought you a starter pack of nutes at most any hydro store only thing that i see you got that you could use is the superthrive.
the reason i say bullcrap on the heat stress my heat is just as warm as yours is i evan run the exsact same fan or did have till mine burnt up the fan motor that is. my clf's i use are the big ones at wal-mart the 135 150 equivilant and get them with-in 3 to 4 inches at most away from my plants. so it can't be heat burn and then there's noway it's from being to close to the bulb. so that leaves to much nutes or nute lock-up from the ph being way off. how often do you give them nutes and at what streangth. also what is your ph of the soil and the ph of plain water you give them and the ph of the water you give them with nutes mixed in. to chech the above named stuff in the soil you can goto any rural farming store i think it cost like 20 bucks to test the ph and n-p-k 10 times each the one i got is called rapitest soil test kit they might evan sell them at home depot but not sure and after doing those tests once at the begining of planting then every month there after you should be able to get your plant straightened out. but on first glance i'd say nute burn or ph way off but most likely nute burn