Question on my first AG grow seedlings!

Hey all, this is my first grow in a AG and I've got a few concerns about my seedlings, they are gradient yellow to green as the pic shows - Ive got an airstone in the res and my Ph is reading 7.2 (tad high I know) I think its the Ph from what Ive read but Im not entirely sure, what do you guys think?

Lightup.

P.s. sorry for bad pic quality Iphone cam is terrible!

they look good man, you want your pH to always be at 5.7 to 5.8