Potassium deficiency? Is it worth fixing this late...

a fade is normal, but spots and other symptoms are not ideal. Check pH. eliminate things that cause the same symptoms but that you can measure to some extent. only put things into your substrate or res when you are certain. If leaves are dark, irrigate with ph'd only water.. .no ferts... see how it reacts. Any fade, jump back on regular ferilization schedule. If pH is on and other factors ruled out, you can feel safer about boosting whatever you've deduced as the problem... slowly. if you see the problem again, adjust ratio or what your ferts are to counteract the deficiency and should avoid it in future. Approaching 7 weeks in bloom and my canopy isn't perfect, but i don't have rust spots or necrotic bits here and there.