Help! First Grow (Various Strains)

Plants are almost 2 weeks old.. Ph is at 6.5. using FF Soil.
i dont know why some of the leaves are turning brown.. could it be over watering? I could really use some help...Thanks

yip i have read alot and seen alot of pics n it does lk like to much nutrients . i am a new grower but from wat i learned you need breack the youngsters in . i wld flush with clean water and only use 2/3rds of the recommended dosage of nutrient at the max then as they mature u can start to use the correct mixture. i never used full mixture until they were ready to bloom . i also use a ec meter as your food makes the ec level rise . for your u want start at low end of ec limit 1.2 up to 2.8 max but i am on full feed mix and my ec is 2.0 average .