That's likely at least part of your issue then. Stop supplementing cal/mag. Canna's coco line is formulated for tapwater and does not need additional cal/mag unless you just happen to have a deficiency in that area for your particular water source.
How old is that plant and how many times have you watered it?
Wait, so you're watering 50% of the time with plain water? THAT is probably your main issue, you should never put plain water through coco as it will upset the cation exchange capacity of the medium. Smarter people than I can explain a bit further, here's a link about it if you're interested:
Not required but I use it for older seedlings and vegging plants, not usually brand new seedlings. It probably isn't going to hurt, but again, I recommend you keep the mix very simple with only A+B until you get the plants back on track. The more stuff you have in your nutrient solution the harder it will be to determine what (if anything) is causing the issue.
I would be pretty shocked if you don't see a noticeable improvement in under 48 hours.
Yeah, I would listen to the hydro store dude. He probably knows how his products work w/ more people's grows. I grow w/ coco and perlite. It works for me, your mileage may vary. The thing I would change is your ec level seems a little high for a plant so young. I would drop that ec down to 0.9. and feed when your container is light.
