Just quick perusing and I want to go back to the issues you were having a couple weeks ago with the high EC readings that wouldn't come down. That is how a salt accumulation acts. Even though you are watering regularly, there are some pockets that likely got dry and became hydrophobic so even when the coco is watered, it doesn't wicker into those dry areas. Occasionally the outer band of the pocket gets moistened and then we see that EC number rise and it's why we see it keep rising even though we are putting more water through, because that pocket is beginning to get diluted. The way out of the mess is to move a large volume of water very slowly through the medium until the EC number looks good.
What can happen is we see a runoff value and think it's good but it's a good practice to take a second reading after more water has come out and check if it's higher, lower or the same as your first reading, because it tells you a lot about what's going on in there.