Hi mate, am using the same combo of Bio-Canna range in Canna Terra pro dirt and have had a few yellow leaves pop up around day 15 of flower. My local shop advised against PHing this stuff as it ruins the bacteria etc. Curious to know how long you have been using this stuff and if a N deficiency is common early in flower with it? I'm going to try top dressing with Worm Castings.
@snwaddct,I think it is not a nitrogen deficiency but calcium and magnesium, however this is the second time I use this fertilizer combo, try adding calmag to the nutrient solution should be better, otherwise try washing the roots for 1 week at least 3 times and then slowly you begin to give him the fert 💪💪💪