The yellow spots that were seen last week have mul...

Hi there fellow Grower, this is calcium deficiency plane and simple. This deficiency can be caused by excess or miss of something. I had that with my NL if you have the curiosity is possible to see one with severe simptomes in my diaryes. Follow a few ideas: 0-always flush the coco before use, specially the brick ones and cheap unbranded. That removes the salts that might be there... You can still flush in any case just be carefull not to overwater the plants. 1- use some bennies if you have acess, Rechare is an example i know it works very well and covers many areas os issues like PH and nute Locks, the issue you have for instance, that will regulate vell your root zone so it can absorb well and is always estimulated. You can pair that with the cannazym, if you wish no woryes. 3-Keep the base nute and cut the boosters like Rhizotonic till the spotting stops, usually you aim for half of the schedule suggests and up slowly feeling the plant. I cant comment specifically on the Canna line. Also Make sure you are not aplying cal mag on every water if you use tap water, generaly one a week is enought to correct deficiencies. 4-use good watering habits, at the point you are you can water the base of the plant and a bit around, no need to soak the hole medium, it will take a lot to dry when its soaked and the plant ant brearh well or starts to sufocate. When is time to water you can feel the vase weight and the top os the soil sticking to the seccond knukle to see if is moist! 5-Check the runoff and see the EC that is coming out and PH, like that you will have an idea of what is in it. Good luck, happy growing!