Plants in need of help

Ok a first time grower here. These are in a room with good ventilation and have 3x250 watt MHD and 2X150 watt HPS above these aproz 2 feet from tops of plants. I have been using DNF Gro formula Part A & B in proper portions as well as a very week aditive of miracle grow aprox 7 drops per 2 gallons. The temp is a little warm but within safe levels. I am not sure of my humidity. These plants are about 3 weeks old and over the past week i have seen problems starting first some leaves were mis-shaped and one part of the leaf would point up and the other down. Thats seemed to correct itself though. Then on one of the plants the bottom leaves stated to dry out really fast, this happened when I think I made my first mistake. I cleaned out a bottle to mist with, but it had cleaner in it. I had washed it out with hot water throughly but I guess I didnt do a good enough job because when I got up the next morning i tasted the water after seeing my plant and I could taste the cleaner. I bought a new bottle for misting that day. I also noted my PH was about 7.6 out of my tape a couple days ago so I have been correcting it to about 6.2 before watering. I noticed that the plant i misted with the cleaners in the watter allot of the big leaves dryed right out and are cracking, also the new sprouts are very tight. I looked at pic and thought it was a zinc problem so that is why I started to use miracle grow as it has zinc. Over night the tight new leaves more than doubled in size I was very surprised. they are still tight but they are growing. Also on another plant i noticed little brown spots at the tip of each point of the leaf. Not sure what it is there are a few possibilities. have a look at the pics and tell me what you think. Thanx alot