Some Problems (Yellowing, Browning...)

Well, they don't seem happier... The problem with the browning seems to get worse really fast. Here are some new pics (Day 40 in 12/12):



The leafs on pic 2 and 3 were healthy just before 2-3 days. The browning affects only one of the plants. This tells me that it's not mold.
Btw, this plant has problems from the beginning, but surprisingly it has the most trichomes.

What should I do? Maybe next time water with even more P and K?
Also, I can't get the RH down much... It's 70-85% (was 95%).

Thanks

P.S. Here are some pics from day 41 Veg. The RH was 45% - 60%:

I can get the plants back to this room and the RH will go down by 10%, I suppose. The problem is that the temp is higher there. I think it'll go up to about 90F with the HPS on.

Yours is looking similar to mine. My humidity is @42% in room (38% in its box) and I run humidifier 24/7. My temps are @80-84. I thought maybe I was over nuting so I exchanged a day with just water. She looks the same tho. I'll keep an eye here for what you're doin.

I think I found another clue. I measured the PH of the solution I watered with last time. Surprisingly it seems to be around 8... That is very strange, because the water I use has PH of around 7-7,5. Also it's strange that I found some kind of particles at the bottom of the bottle the solution was. Maybe Epsom salt?
As I know most of the fertilizers have lower PH. So...maybe the Epsom salt raised the PH?

Maybe I'll use a little vinegar to lower it the next time I water.