Whats up with my plant

This is the first plant I have tried to grow using a bubble bucket. The ph is 5.8 -6.0 max, ppm around 990, temp in the room is between 82 to 89 degrees, the rh is low like 35. I put a humidifier in the room last night, woke up this morning and the tips of the one leaf are dry and curling. Maybe the ppm is to high, do I need to flush the plant and drop it to say 500 or so. One other thing the temp of the water in the bucket is about 80 degrees. The light I am using is a 400 watt hps, and it is about 24 inch above the plant. This is a bag seed, I have no idea what it is, I just wanted to see if I could grow before investing in some top dollar seeds.

 

Trying.... I got the exhaust fans running and 2 fans inside the room. The only other option I have is to raise the light again, maybe I will try 3 foot away from the plant, just worring that it may start to strech. 3 foot with 400 watts is that a problem... but of course there is a problem now.

 

Not really, without doing some modifications to the reflector myself, which I maybe forced into doing. The temp now is 81.5 with the rh at 49. I guess I should have bought a better lighting system, but it is to late now…

 

Ya...I won't go over two feet, you right.

 

up date.....I got the temp down, There is about 2 inches of new
growth it is nice and green and looks healthy, the question now is it normal ( if you look at the first pic) those large 3 leaf stems are starting to get yellow blotches, and they look as if they are dieing, the rest of the plant looks very good.