@303 DUB I'm a bit more familiar looking at the "profiles" (NPK) for various systems, though canna sucks as I cannot find guaranteed analysis to tell here. If you would like, I could figure up what your providing for ppms and that may help too. There are quite a few people on the forum here that use ppms and profiles with coir. To figure this though, I'd need a couple things from you. First, how much does the 1/4 tsp of that Kool Bloom weigh? Also, if you can list how much your giving of the Canna A & B. Finally, if you could list the guaranteed analysis (percents of elements) from those bottles; as well as the weight and volume listed on the labels. I can at least figure what your providing atm and that may help make some relations here. Oh and are you using R/O or tapwater?
I don't want to put information in that's out of place; like I did with my last post lol. Though I suppose there was a couple things recently that Sea and I discussed with Ca and K, but that isn't medium specific per se. I suppose I can brief on these aspects, so that its' "out there" but not necessarily relating this to your case.
There is something called the "Viets Effect" which is an interaction between 2 elements. Here, the presence of one element can dramatically increase the availability of a second element. This effect is most significant with Ca and K. The presence of a small amount of Ca can drastically increase a plants ability to uptake K.
However, on the opposite side of this spectrum; Ca is antagonistic to K overall and High levels of Ca will reduce the uptake rate of K in plants. Very high levels of Ca can actually reduce the uptake rate of K by as much as 30%.
For your situation I would need to look more at the profile ppms, but I suppose it may be possible that; If what your seeing is a K- (as per Sea) you could be getting some antagonism with the Ca. I would think you'd have ample K since your using the canna and kool bloom, but need to figure ppms first. Your pH being a little off wouldn't be reducing availability of K directly nor should there be a lockout.