Hi Gingerbang, I'm a canna user and thought i'd throw my experiences in.
Exactly 1ml of Both cocoA AND cocoB in my water (which is hard at about 0.6 ec) will leave my water with an EC of around 1.5
This is about right for a 16-20 inch high plant still with a good 3-4 weeks growth behind it.
You'll get to the point where you are reading your plant to asses whether it's all good. (It sounds more complicated than it is)
You want nice lush but not light green leaves that are laying out flat or reaching to the sky. If they are pale, then they need more food.
If they are burning at the tips (not the very very very edge of the tip - that can sometimes look burning when its not - you'll see a couple of mm of yellow/brown) then the feed has been a bit strong.
Something i've had success with is finding a strength that they are happy with and then every watering go up by 0.1 EC to see where the burn starts, and when it does, back down a couple of points and give it a couple of waterings like that and then start going up again.
it's fiddly but gets good results and teaches you to read the plant.
Another tip for A and B i could offer is to measure them out precisely. I've tried to be ham handed about it and just throw in 2ml(ish) of both A and B straight from the bottle.
This slight imbalance has given my girl N poisioning early on. (Dark leaves with down claw tip and rolling in leaves)
Just use a pipette to measure and you'll be golden.
Water to a decent amount of run off to keep the coco nice.
Blue ^_^
