Skinny Leaves and Brown Tips

So heres a basic run down. I've got 4 plants grown from seeds all of which were just collected along the way. i have no idea about their origins. i'm using a t5ho and am currently 5-6 weeks into flowering. The buds are looking ok but a few of the plants have all brown tips and very skinny leave. I suspect that the plants showing these symptoms are of the same strain as the characteristics are very similar. Not that it may matter but i'm pretty these plants are also sativa as they doubled in size after swithching to flowering. I use bloom solution every other watering and have never checked the ph level. Also, i'm sure the root system is being strained as the plants are about 4 foot tall and in 2 gallon pots.

Burnt tips is from over fertilizing. Skinny leaves is sativa or low humidity will do it.
Ya should be watering every day now that they are that big in those 2 gallon pots.