3 Clones 3 Strains - yellowing, help

these clones are on day 17 from the day i got them
im using foxfarm ocean forest potting soil and perlite in a 3:1 ratio
600 watt mh currently for vegging
temp doesnt rise above 85 humidty is low ~25% (can raise if nec)
its on 19/5 lighting schedule
ive fed these guys one thing, a week ago, urea 1tbs per gallon and gave the 3 girls a normal watering amount, is this Nute burn of the nitrogen variety?


Blue Dot: (healthiest of all the clones at meaty 9")

Top shot



White Widow: (the smallest of all the girls at 6")
Extremely small yellow dots


Top shot





super skunk: (shes extremely tall, already 12")


Top shot

thanks and ask any questions i have pictures of everyday of their life


i will be starting a grow log one of these days but here is a pic of my day 41 veg PPP from seed

 

so i should flush each? im about to transplant them into 5 gal buckets should i just do that or flush first?



thx bro

 

im trying to get those girls to catch up to my ppp so i can flower them all at once, whats the best way to do that?




im thinkin 2 more weeks and flower them all under my 600 watt hps..... that will put the ppp at day 55 haha

 

bump


mainly for dier