When discussing the issues with my local shop guy he thinks it is under fed and possibly too hot in the tent. He gave me a sample of cal mag and said it would take a week to recover. We shall see.
That doesn't answer the questions I had. How much of a fert dose do you give and how often? What is the distance from the light to the plants? What kind of light are you using?
After a week of getting more nutes the plants are recovering nicely. I added PK and cal mag to the regular feeding schedule. New growth looks good and the defoliation has subsided quite a bit.