hwhobbs

In my opinion your plant looks kinda small for 26 days, not a lot of growth, altough the uppermost growth looks very healthy. I think you need to start fertilizing your plant, the leaves are turning yellow because of deficiencies. Also, check pH runoff to be sure that's not the problem.

edit: this should have been my first question, what kind of soil are you using and what's the N-P-K?

I just read your grow thread and you should only be using about .5 ml of ST per 3.781 liters (1 gal). That's like 1/4 teaspoon.