PH question

Im growing in coco and adjusted the water to break down the coco bricks to 6.0 roughly. I decided to test runoff and noticed it was extremely acidic. I'm having to use extremely basic water for my runoff to be in the correct range. Should I continue to use basic water so my runoff is in the correct range when watering plants in the near future. I'm just not sure if I'm doing this correctly.

I've flushed the shit out of it with water ph'd to about 6 and it seems to be stabilizing. My runoff is a little over 5 now.

Advice - Don't measure run-off. Only measure and pH what's going in.

I only check runoff for ppm.