Pistil burns in the 3rd week

based on skinny new growth with chlorosis, you probably are feeding too much p or k - common myth that these need to be boosted despite the fact proper research shows no gain to flower mass nor potency. The burned pistils could be from the light too close or if you have a fan directly blowing on them - both can cause that early pistil death. Could be from the light being too powerful too - symptoms would be similar in the 'hotspots' of central area under the light but not so much in weaker areas of light hitting canopy. in flower i'd suggest these ppms... 100-110 N 50ish P 180-190ish K 100+ Ca 75ish Mg 100ish S This is a low EC starting point from which you can observe and adjust as needed. Local variables will cause different needs for overall concentration, but the ratios will be good. you may need to increase or decrease dosing in a proportional way... raise each products dose 10% for example would maintain same ratios but increase overall EC. You'll more likely need to go up from there a bit, as i tend to have a higher VPD. Faster drinking = lower EC feed, among other variables that impact local needs vs a different garden elsewhere. hydrobuddy app can take information from labels and tabulate this stuff for you.