Damn topic hijacked. JK. Lots of numbers and big fancy words in there. I agree you can add much more than 8% and have no ill side effects or rather have huge growth. I think it depends on the strength of your solution, your medium, plant size (root size too), environmental (fans, dehumidifier, heat), container type (plastic, fabric, clay), and perhaps more reasons I can think of. I was doing 33% (1 gallon solution to 3 gallon pot) with little runoff (it was starting to have almost no runoff) at transition to flower. No burn and it was growing super healthy. I was using full strength nutes too. But I was using fabric pots, coco, and leca (super airy) with three fans (one being exhaust) in a tiny space. Also it was 3 fertigation events per day, 4 hours apart each (.33 gallons each event)