Nft hydro

First week of flushing complete, leaves starting to yellow already. Not sure if I started a bit early think maybe could of got away with another week of feeding but oh well best smoking cleaner bud anyway. Major breakthrough. Back right plant seems a monster with huge buds. Realised last week that one plant is different forgot I planted freebies and done an elimination so figured out that the freebie is G13 x blueberry headband by emerald triangle seeds. Flowers Def not as big as the CK but still looks good sized potent buds also seems to have some sort of calcium deficiency that I wasn't able to correct early enough . That's the first right plant from the pictures. Not been adding PH down or UP during flushing not sure if you should of anyone can correct me. Just thought whole point of the flush is for nothing but clean water to be in the tanks.