Soil PH or Soil PH Runoff

I guess the direct to the point question is which should I be most concerned about. Soil ph or runoff ph?!?!

Reason I ask!
I have a bluelab soil ph pen and a Apera PH20 ph tester for the water only. Both are in calibration. The feed water going in is ph’d to 6.8. Soil is a fox farm and canna coco mix. More fox farm than coco. Prob 75/25. When I watered tonight I checked the actual soil ph with the bluelab meter and it was 6.0 and checked the runoff with the apera meter and it was 6.5. So a .5 difference between the two reading soil vs runoff. Any advice would be great. Thanks!

Stop checking ph in soil. That's my advice anyway. If you only have 25% coco in there, you'll get the benefits of aeration, but it's still going to act like soil. The only issue you may encounter later on depending on your feed, is K tox. Coco holds it very well.

Any reading you get from soil is mostly only useful for diagnosing problems. Especially if you have quality soil. Nutrient lockouts due to ph are a lot harder to get in soil than in hydro as the ph will vary across the whole surface of the rootball in soil.

The method to check soil pH is with a slurry test. Runoff isn't accurate because the soil has amendments in it. Different amendments have different pH values and you don't know how much of any amendment is washing out of the soil and influencing the runoff pH. But I wouldn't even bother checking. It's not hydro.