First, if your plant still shows no signs of any stress, don't try too hard to fix something that's potentially not broken. However, a few steps should clear this up for you.
-Get a pH/EC/ppm pen, those probe meters even in soil often give little information that is useful. Coco is also not a medium to mess around with when it comes to pH, you need to be as accurate as possible with this. Mix your solution, pH to about 6.0, feed, and go from there.
-If you feel you have pH issues inside the medium already you can quickly correct this by doing a "flush" or I just call it a feed with about three times as much volume as you usually would. Let it all drain out well and you should have replaced the old nutrients in the medium with the new batch.
-Finally if you still want to test the medium, the only way to do this in coco is by slurry. Taking some of the coco from your pot and making a slurry, testing pH of the slurry (again with that pen you need!!). You can look up specifics on this but I honestly never do this myself so I will let another with experience explain the details.
-One more thing, don't let that coco dry out, you wont experience nearly the amount of pH and nutrient lock problems in coco if it stays wet!
Sherlock
