I am new to the growing seen I have a 1.5m by 1.5 m ten with 2 300w 5w led grow lights large size co2 bag 4" exstracter fan with carbon filter attached and 2 desk fans. 2 of my plants was going fine started them on neuts at 1/4 advised on week 2 but another plant was tiny in size to the others. Since then the tiny plant has started yellowing leaves and one of the others is curling leaves I read a sign to heat stress but my tent sits at 22 c 50-60 rh and the led lights both Mars hydro are sat 25" from the plants I will provide pictures from 3 of the plants one tiny one healthy and one curling leaves. Help and advice would help alot. One to not I added a very small amount of chicken manure pellets a week ago after noticing tge change thanks. Also they are bedded in Coco and perlite with a layer of pebbles half way down the fabric pots and at the bottom for air to the roots