Hey Growmie, with straight coco coir, it is critical to adjust the pH of the inflow, you should not be too concerned with the pH of the run-off water. Your only concern with pH is always providing nutrient solution (inflow) that is in the appropriate range for your substrate. Many growers make bad decisions to provide nutrient solution that is outside of the acceptable range in a misguided attempt to correct run-off pH values. This can destabilize the pH of the nutrient solution in the root zone and make nutrients unavailable. To avoid this common pitfall, simply ignore the pH of the run-off and focus on inputs in the acceptable ranges. Good Luck Growmie! 👊❤️🇨🇦