Hi. I am having problems with my plants in coco. Leaves are dying off, showing mag deficiency. I was adding calmag, but problem did not go away. I have checked run off ph and it was 6.4 and even 6.6 on some plants. Yesterday i have flushed them with nutrient solution at 5.7 until run off was 5.7-5.8. After 12 hours I have watered tgem again at 5.7 just to collect and check some run off. It was 6.4-6.5 again. I am using canna pro coir and canna nutes plus calmag and ro water. I have made nutes solution in the morning and ph of it was stable. Ph meter is calibrated. Any help welcome.