You introduced Cannazym and Rizo rather early - they're not really for vegetative growth. You introduce them when your plant stops vertical growth.. Otherwise, they will stop vertical growth. They're products that are meant to work on the roots and remove dead roots and create the rhizophere effect.
With that said and out of the way, what's the height of your LED?
I'm hard pressed to believe you can't find Epsom Salts, but before we even say it's cal/mag.. what's the height of your LED? What's the pH of your water going in and have you any way to check the pH of your water coming out? That's a very strange burn but it's clearly from what you're feeding it as it's most prominent (you say, ONLY actually) in the top leaves and it's effecting the smallest of the sugar leaves..
What nutes are you using exactly? You list a few canna products on the first page - but what do you have at your disposal, right now, to use?