Ok - so yes, you're correct, your plant is using the nutes you're giving it.... the pH is a bit troubling that the runoff is so much higher than what you're giving as the runoff indicates what's actually happening in the "soil" ... and 6.8 is a little high for coco... If you're feeding/watering at 5.8, I would drop that to 5.5 and see how the runoff looks... Ideally, you don't want your runoff to be higher than 6.4.