Seedling 6 days old yellow tips?

Hey guys i have germinated a OG kush seed about 6 days ago and now its a seedling but the 2 tips of 4 leafs are yellow any idea why?

Ph: 5.5
(CF: 7) (EC:0.7)
ProbHumid: 75%
Nutes: Regen-a-root 1ml per liter (Half strength 0.5ml)

no picture so hard to tell, but why give nutes to a seedling?? they dont need any, does more harm than good at this stage

Yep, as Zett66 says, seedlings don't need nutrients for the first couple of weeks or you risk overfeeding them. If you must give them nutrients start with 1/4 - 1/8 of what is recommended and only once per week.