Unsure of my problem

I am trying to figure out what is wrong with my plant, dont have a ph tester so im hoping a few pics may make it easy to diagnose. This is my first grow and have had to make due with what i can, no job, no money, but growin to satisfy a need...... so any help without the "youre a dumbass" would be appreciated!

Can you tell us what nutrients you are using, lights, temperature, etc?

Ph is one of the most essential elements to nutrient uptake, i cant believe u got this far w/o testing ur soil/water once.

its amazing how hard people think it is to grow a WEED. I am using a 400w hps on it, but besides that it gets water minus the chlorine and i was using green light super bloom (12-55-6) on it once a week in water and way less than is recommended, i didnt want to burn them. and when i say less, i would say less than a teaspoon to a gallon. I included a layer of sand in the substrate to help with draining, soil is organic, im thinking its from the heat, but not sure......i have 2 fans on it at all times but im now about 16in from the light and it started showing up about 2 weeks ago.....they were pretty and green til then, and the bottom leaves are still green and pretty but curling up....i dunno!!

well what are your temps if u think its heat?

Just judging by the 3 pictures i can tell that
A) whatever youre feeding them has way too much magnesium. WATER. WATER is king, queen, whatever its the best.
B) Back off those lights, or get some better cooling going on. Are you circulating the air inside of the space?

Either way, looks like too much Magnesium and Heat

I have been doing nothing but water for the last 3 weeks to try and straighten it out, still more of the same, thats what makes me think its the light, its been about 85 in there so i opened it up a little and its now down to 78 (temp). I also moved the plant away from the light so its getting the light indirectly.