to tell you the truth, you need to go to the canna website, they have a feeding schedule...use that
now, that same feeding chart will tell you the ppm or EC the water should be, start from this point for whichever specific week you are on, just follow directions. During the week as the water gets consumed and the ppm decreases, replace with water and add more nutes according to the weeks specific dosage, the ppm should go back up between the state range on the schedule, if its still too low and your res is full, just add nutes, but add them slowly and then ph your water......BAM! done
do this every week