thankyou postmandave,
when i fed her last i mixed 2 ferts together 35-10-10 and 10-30-30 so if it is K then it'll have gotten some as well as a little N boost,i don't have a tds/ec meter so am unable to test feeds and run off,i've had to play it by eye and touch wood haven't had any problems in previous grows,yellowing actually seems to be improving since feeding so fingers crossed,though if it gets worse i will flush

mulletman,thanks as well,you know what though,after the 2 weeks it took to root that plant,i only actually vegged it for 26 days under a 16/8 schedule,so longer veg periods might not be needed