beginner grow

Wow, It was f*&$£$n freezing this last 2 weeks, last week I made a cellotex house for my grow tent as its in a cold container indoors but outdoors. It worked a treat, inside temperature was a good 5deg warmer. but I did have major issues last week, yellowing on leaves, burning on a few tips, and as this is my first serious attempt at this (last year I grew 2 clones, easy he says, got 4 oz dry was well happy) I was all over the place, but I stuck to my principals and changed one thing at a time and monitored daily. From seed to sprout really has been 3 weeks in total, I ran them on ph balanced water but no feed, week 4 they went into 5l cloth bags and clay pebbles and coco and had half feed (all of this has been decided based on what I have seen online or been recommended). Now seeing as I don't have a dripper system and am hand watering its a fine balance between giving them too much or not enough, I had the lights at the wrong height and managed to mess up the feed ratio the first 2 feeds but I think th major problem was light burn, the Zeus 300w is a really powerful light compared to my sodium, I mean, visually its bright, I have now moved it up to 24" turned it down a notch or two and balanced out the feed, they all seem to getting better, I found a random sprout, I don't know where the hell it came from, I think there was an extra seed in my seed pack, winner, but she is struggling you can see it in the tiny pot on my images. Well, they are growing, not as quick as I thought they would, I look at other peoples photos and mine seem tiny compared to some, maybe something is wrong in my setup, maybe they got a better camera than my phone, I don't know, learning curve this one. I have ordered an aeroponic system for my next attempt, I did ponder moving this lot, but figure the tank, pump and pipe work should be super clean, so don't want to go anywhere near it with coco fibres attached to the roots.