Sensi Skunk Auto - Sensi Seeds

Planted the seeds on 11/12/17 straight into coco+perlite mixture (coco from a brick) - sprouted in three days. These are 16 days from seed and I'm worried they're a little small. I'm growing in pretty controlled conditions, got passive intake and an extractor fan - ambient temps dont exceed 30°C in the grow room. 300W CFL hanging about 5 inch from the top of the tent. I water every 2 days with 1L of nutrient ph 6.5 water, containing canna A and canna B (1ml/L). The smaller plant (the Runt) popped a day later and seems to have yellowing on its leaves - not sure why that is but any tips or comments would be appreciated! (: UPDATE: 31/12/17 - Day 20 The plants have definitely increased their rate of growth, seen new leaves come out over the course of 24 hrs or so. Made a change in lighting from 24/0 to 18/6 and i think that's made a decent change. I'm struggling to keep the temps in my grow room down, they get up to 34-35 when the light is on and then down to like 25 when its off. know how i could keep the temps down? im growing in a closet so ventinf outside just isnt an option. I have an outake and and an intake fan although both of them arent extremely powerful due to restrictions on grow conditions. Also thinking of repotting from 1gal to 8L? initial plan was to have 3 autos in 1gal root nurse bags but the third didnt pop, would increasing the bag size have any worthwhile impact on the yield? the runt suffering from some nute burn at day 20, gonna halve the feed not sure if i even need any right now probably do because im growing in coco coir as compared to soil