Calibrate the ph pen first, do a solution of 6.0 water and analize the water that comes out. In my opinion the membrane of your pen is gone. Your plants looks healty . If the ph is still high do another flush with 4.5 ph water .
You have to take care of your ph pen putting the membrane under preservative liquid when u are not using it. Hope to be usefull and that u can understand me in my englsish 😂✌️🏽