During flowering it is natural for the fan leaves to yellow and eventually die off. It generally starts from the bottom up on the old growth due to the lack of Nitrogen in flowering feeds.
A simple aid is some watered down clean urine, honestly Ive used it myself. or give half your next feed to some of your veg nutes. As has higher level of N. Hope this helps!
She didn't have the yellow, but she had the "thirsty droop" that they all seem to get about 12-15 hours before I water them. It was almost overnight that the yellowing took place. After the watering most of her other drooped leaves were perked right up.. it was just a lot of the fan leaves that didn't recover. Looking back her last watering was 8 days earlier, so I don't think it is an overwatering issue, but ill keep her checking her twice daily, when the lights come on, and before they shut off.
Just a note. If you let the plants get dry to the point they begin to droop, they have dried too much and there can be a small amount of stress induced. Not a problem once or twice, however, if it occurs between every watering or feed it could adversely effect yield in the end.
The danger in watering comes from the bottom couples inches in the pot. On the one hand, you want the soil to remain damp throughout the pot so all the roots have enough, but you also need to keep the bottom soil aerated - you don't want it to go anerobic. If you water too often, you have trouble, but if you let the pot get too dry, you lose roots.
I like to soak the final pot at transplant, let them soak that up until they get dry ... resoak it ... then try not to ever let them dry out again. By that time, the pots are filled with roots, and the water in the lowest soil is easily absorbed.
Let them dry well in early veg, and then keep them from drying after that. At this stage, you want to catch them before they get very dry.
So lights came on tonight and she seems a lil more green...(I snapped off the ickypoo yellow leaves lol).
I just can't believe how fast these ladies are growing. I added another Purple Wreck and another BC God Bud to the flower tent today. I am rapidly running out of room in there... not sure I will be able to keep adding much longer!
Here are some pictures from the flower tent as of this night.