1st Grow Ever

Mon - Start of week 7. Just watered and fed the plants. Finally got around to leveling the plants off so they can all share the same level of light. Last week was the first full week of stretch, they almost doubled in size. They now are about 22", 16" 10.5" and 8" It will be interesting to see how much more they grow. Wed. - Noticed a bit of yellow and brown spots on leaves of all plants, none in newer growth, all in the bottom 1/3rd of the plants. I suspect that the PH recommend by the CANNA feeding schedule 5.8 - 6.2 might be a little low causing PH lockout. I suppose this could be an actual Mag or Cal deficiency but as I use tap water left out for 48+ hours, and my water has a moderate hardness I do not think I need to add anything, just get PH up to the 6.3 - 6.8 range. I watered today with no nuts just with PH 6.5 water. Will keep an eye out for new spots. I am photoing the plants and studying them to see if there are any new ones. Friday - Fed with nutes in 6.5PH water. Plants still growing at 1 to 2 inches per day. Not positive but it seems the signs of Calcium deficiency are still there, noticing more brown/ yellow spots. I believe the PH is under control at this point, so I can only assume the issue is an actual calcium deficiency. Will add some Cal/Mag at next watering. Sun - End of the week, watered with no nutes, only Cal/Mag at 1.3 tsp per gal. Fri - Did not notice new spots, plants are still growing at about an 1 - 2 inches a day. Fed with PH 6.5 nutes per schedule.