I'm going through the same shit, looked just like that early on. Tested my runoff and it was ph 4-5 !! Ended up I did not rinse the coco i was using , trusting the manufacturer who boasted you don't need to. So my advice to you: flush with ph 6.5 water and test runoff ph. Make sure you get the test runoff water early on in the rinse. Maybe you have excessive salt build up.
Edit: what is that round thing in the container? Is that a fricken tree? Ther's ur problem right there Vern. (if it is)