FIG. 1 is a front view of the pH probe assembly. FIG. 2 is a front, top and side view thereof. FIG. 3 is a left side view thereof. FIG. 4 is a rear side view thereof. FIG. 5 is a rear, top and side view thereof. FIG. 6 is a right view thereof. FIG. 7 is a top view thereof; and, FIG. 8 is a bottom view thereof.