Major Yellow

Well, I'm about 5 weeks into flower, and I am having a major fan leaf turn to yellow. Reading around it sounds kind of normal, but it is still scary for a first grow.

A few days ago a few leaves started turning, so I added a bit of nitrogen to the last feeding. If anything this has sped it up. Now about half the leaves are yellow, but not burnt.

Any ideas?

Were they transplanted anywhere in their life? If the plant has been in the same medium for it's entire life, odds are the ph is out of range. Buffers in soil only last so long. Most of us transplant once or twice throughout the life of the plant to provide new buffered medium for the roots to grow into. It also causes much more efficient use of the medium by the plant.

Look for the troubleshooting form in the Plant Problems section and fill it out so we know what we are diagnosing for you. Anything suggested before we see that is mere speculation at best.