Stay away from time release shit...You feed them..Easy to add more...hard to remove existing..Also watch that you mix your mediums well..pockets can cause nute probs. I do replace my soil at the top of pot to remove those white (salts) clumps..I would re-pot, water once, no nutes and wait and see...
In FAQ in the Water, nutrients & add. section theres a whats wrong with my plant diagnostic section..there is also a chart w/pics.just can't point out where at the moment..It's there though. At the moment I'm using a basic 20-20-20..
I never go over 5ml per gallon....when I did, I lost a crop.. give it 5 days with minimum water & no nutes...see that yellowing doesn't progress...If OK start GRADUAL reintroduction of nutes... Good Luck..