Just some thoughts.
You may have damaged roots, in flower the root recovery is almost 0.
Rule of thumb is 300ppm over what's going in for runoff.
Things really depend on your vpd. Dry side plants have to pull lots of moisture in if they can't use the nutes in it builds up and if gets too high will burn the roots.
I like coco but to me drain to waste is just that, a lot of waste. So I feed on the conservative side with little runoff. I'll give plants a good rinse every so often. Monitor runoff. If it gets above the 300 above feed. Cut back.