Please Help My Little One

My plants have been in veg under a 125W CFL for about a week and a half now. They are all doing great except for this single plant. I can't tell if it's a nute deficiency or whatnot. I've tried comparing to many of the photos on the site but I really can't tell...

The pH is 5.7 although keeps climbing... I keep bringing it back down was going to research that on here next put you can't search for two letter words so pH and UP are out These plants are on 25% strength nutes using sensigrow. Purified water... 18 / 6...

All the images are of the bad and one thrown in there as a comparison from another one of the plants... you can see the leaf is turning a purpleish color from the under the leaf shot...

Please help and thanks in advance!

Anybody? They're pretty good pics at least

You plant looks healthy, it is in your head!. The slight purpleish tinge is just the phenotype, not a sign of illness.

I only notice a slight discolorazation that is it nothing major. You have a great camera by the way. Great shots!

Thanks it's actually just a little Canon SD point and shoot but it does a nice job And thanks for the stress relief! It's not growing nearly as fast as the other though