I have 2 Vertex XL/2 diffusers approx. 175 ft apart in my rectangular 7/8 acre pond at a depth of 8-10 ft. Air supplied by Gast 0523 pump. Once a month I close the ball valve on one XL/2 diffuser, sending all air through the other, then reverse the process. My thinking is the extra air flushes pores that may have become blocked during normal use. I seem to have a better boil afterwards. I haven't felt the need to do more yet.
