flushed now their yellowing????

I NOTICED THE LEAVES ON MY PLANTS WERE CURLING DOWNWARD FROM THE TIP AND THAT THE VERY TIP AND EDGES OF THE LEAF WAS BURNT (BLACK) NOT BROWN NOT REALY TIPICALLY WHAT I AM USED TO WITH NUTE BURN IF THIS IS WHAT MY PROB IS.SO I FIGURED THAT I WOULD PUT LESS THAN HALF OF WHAT I USUALLY PUT AS FAR AS NUTES GO. A MINOR FLUSH.2 DAYS AFTER I DID THIS I AM HAVE 10 TIMES MORE YELLOWING.THE YELLOWING IS STARTING FROM THE LEAFS EDGES AND MOVING INWARDS.NOW THE THING IS DO I FLUSH AGAIN BECAUSE THIS IS BEING CAUSED BY A BUILD UP IN THE SOIL AND I JUST DIDN'T GET THE BUILD UP OUT OR DO I NOT FLUSH BECAUSE THAT IS WHAT IS CAUSING THEM TO GET WORST????I ORIGANALY THOUGHT NUTE BURN BECAUSE OF THE BURNT TIP THE CURLING DOWNWARD AND TINY TWISTED LEAVES IN THE BUD.ONE MORE THING IS ON SOME LEAVES THE TIP IS HOOKED SHAPED.I SHOULD HAVE MENTIONED IT STRAIGHT FROM THE START I AM IN WEEK 6 OF 9 BUDDING RUN OFF IS 800-900PPM AND THE PH LEVEL IS 6.3-6.5 TEMPS ARE IN CHECK

THANKS TO ANY ONE WITH ANY IDEAS OR HELP

If you are in week 6 of budding, and your flower time is supposed to be 9 weeks, you will have yellowing leaves, and more and more leaves will yellow. Some strains do this some are not as prone to it. In the last weeks of flowering your plant is die'n thats what they do and thats what you want them to do, it forces them to push all its energy into producing as much THC and trich's as possible before it dies. Pics would help, but I would say you will be ok if you only have 3 weeks of flowering left. You shouldn't have flushed though when you started to see yellowing leaves, because now you just deprived them on nitrogen which will cause more yellowing, shoulda left them be then flushed a week before harvest.

Thanks for the info and your time. I hope that this dosn't do any damage to the yeild.

siksol explained it pretty well, its just the leaves dying due to old age