help with seedlings

hello im running a 10 gallon 6 plant hydro setup with a 400 w hps and im at day 9 and the lil seedlings are just starting to increase the size of its first leaves and started to get bigger and my question is why are 2 of my plants turning yellow in color, not bright or dead yellow, just a shade of yellow, the nutrients are 1 tsp flora gro , 1tsp flora bloom, 1 tsp flora micro. the light is 1 foot above the seedlings and the roots are growing very well into the water and looking nice. any ideas on why they could be yellowing, or will they grow out of it? they dont look droopy or anything. thanks

bump, do you think i overfed at 1 tsp of each per 10 gallons or not enough, maybe thats why they are yellowing? they continue to grow good

Pictures are a MUST... and what is your PPM and PH?????