mikee i have used cann nutes for a few years now and the canna grow chart is based on ro water so if you are using tap water make sure you leave it sitting for at least 24 hours to remove the fluoride as it affects the plants worst than normal when using canna.Are you using any of the additives like ritzotonic or zym?I use the ferts once week starting with a ppm of 200 building up to 850ppm in veg but again this can be strain dependant.Less is best with canna nutes as they can burn some strains with higher ppm but ive never had nute burn or deficiency in soil grows keeping within this ppm range with canna.By the way the plant looks good just keep doing what you are doing.be safe the postman.