Severe Yellow Please Help!!

Hey guys, I have a big prob and cant figure it out. Im 3 weeks away from harv.. i think it zinc can anyone help?? using a 600 hps, temps allways in 70's, humidty 40'-50's, keepin ph around 6.5 using liquid ph tester(i might have been adding to much ph up and it could be slightly above 7), using FF nutes grow, tiger, big bloom ( amount FF scedule says to use) with watering every 2-3 days, have in vent and out vent but air gets stale from time to time in room where in vent comes from

ive been flushing it last 3 days with just water with the right ph and it seemsto keep getting worse... please help!

looks like your fan leaves r doin what they do naturally in the late stages of flower could be wrong tho but plant does seem health everywhere else.

the tips of majority of the new leaves are yellow then browning around the bud.. the whole crop is way to yellow

hit em with a little bit of nitrogen ???

my bad flush them check the ph of the runoff than if your good with the ph hit them with some nitrogen

ive been givin it all foxfarm nutes every water... anyone think its because of ph posably being slightly above 7 and locking the nutes out?

possibly whats your medium you growing in ?

soil...pro mix.. thanks again to everyon helping out