hydro prob cont

hello there i finally got some pics of my problems. I've been growing kk for some time now. veging 5 weeks then moving them over to the 12 on off room. I used to get 1.5 to 2 lbs per plant but now like .5lbs. the leaves start to turn yellow after the 3rd week in bud. its mostly the old ones and the tops first, then spreds to whole plant. I've tried everything known to man i think. I have 2 places with same clones to start. 1 place has right now the food at 1000 to 1200 ppms the other 1400 to 1600 . 1 has 1 part food the other 3part, but still the same thing goes on at both places. ph is 5.7-5.9, rez temp is 65 deg,humid 30-50 % temp 75-80 and co2 1500. I just dont get it. i use calmax,power worm,b1,floralicious, big bud, humic fulvic and zyme. Can anyone help? mabey it is my clones to begin with it is a 10 yr old strain?