Yes, if you have a flushing solution, Not sure what Canna's is... I use FloraKleen by GH, Use it!!! Absolutely
I would want to know the run-off and inflow EC values on the others. I can give you a lot of advice about how to manage the Coco, but it all depends on knowing EC. I discuss flushing based on EC in my guide also.
But I don't need to see a meter to know that the EC of that one is way too high, so a good flush with agent and then resume fertigation (12 hours later if using flushing agent), probably with weaker nutes and more run-off than you have been running.