IMO it looks totally normal:thumbsup:. It looks like the yellow is starting with the older fan leaves??? Your leaves are going to yellow as the plant comes to the end of its life, its normal. I would just stick it out, it really doesn't look like you have a problem. Did you use nutes and are you still??? If you want to see what your older fan leaves will most likely do, check out my log in my sig...Some won't yellow as bad as the one in my log but it depends on the strain and many other factors too. Yellowing is not always a bad thing:thumbsup: