Subbed fella!
I notice you've been having to flush, and been suffering from some nute burn issues...
One thing I can see being a problem is the soil / coco mix. They really are two different growing methods. I mainly use 100% coco, and feed the plants every day @1/3 strength. If I'm growing in soil, then I wont feed the first couple of weeks, then it would really only be a feed every 7 days or so, plain water in between.
What coco are you using? I stick with Canna Coco, mainly because it's thoroughly prepared before sale so there is no residual salt in the medium, some other brands of coco, especially bricked coco can have a very high salt content and requires a lot of flushing before it can be used.