Here's some more crap pictures, can't really tell from the pictures the problem. The problem is spreading to other fan leaves.
I'll have a look at it outside the tent tomorrow.
Been thinking on things, I upped the potassium and phosphorous yesterday, only a little, maybe it's a lock out.
I think I have a few choices about what to do.
1 - leave alone, it's a natural part of the growing cycle, like muddy says in lifecycle of autoflowers thread.
2 - I have a bit of soil which has silicium flash in it and startrex in it, I couldn't fit it in the pot when I made the pot up. I have 300ml of soil, I could do a little top dress.
3 - give a feed of orgatrex, which has most of the recommended nutrients.
4 - add a bit of magnesium.
5 - just feed water for a while
Any ideas what people think?
Thanks for looking.