I mean is that the ph of the nutrient solution before you give it to the plant, or the ph of the runoff coming out of the pot after you water.going in or coming out?
But I gather you are using one of those cheap ph meters you stick in the soil. Those things are not to be trusted. Only way to truely know is test the nutrient solution on both ends with a proper calibrated ph meter. Anything else is just guessing.