Regarding runoff question with coco grows ....in my limited experience with 5 grows
It is my opinion that it is not a reliable indicator of what is going on. The literature I have read from those growers who use coco are in favor/support this theory. However, there are those growers that do not support this and depending on the situation you are encountering it may help in some situations. Again, for ppm/tds and what the plant is doing with the nutes I have found it is not a reliable indicator, but you will find people who will disagree. In the field of botany, there is so many theories/debate/disagreement. You must find what works for you and just when you think you got it, you change a variable and that may effect other variables in your grow and things go down hill. That's what makes it fun for me. Problem solving. If all grows were the same, I would get bored and not grow....every grow is an adventure regardless of the outcome....enjoy the ride my friend ...your plants look great