A lot of yellow/pale green leaves 31 days into flower

heres some pics mate

Have we flushed this medium repeatedly?? You have have a bit of nutrient lock-out if the Nitro doesn`t make a change in a day or two. If it were pure deficiency you`d see fast signs of uptake if your stem and growth system had enough and proper growth. I`d be thoroughly flushing and resume feeding, FULL vegetative feeding. I`ll stay put

KC

Also if the leaf tips are now curling up and browning, the plant now seems to be exhibiting signs of mag deficiency. Get yourself so Cal-Mag or start minorly introducing Micro`s after your flush

KC