I've been tracking limited environmental monitoring (I have funding limits, per management) within a small but significant area of Zone 1 equipment surfaces, and have been unable to break out of a high Aerobic Plate Count trend--sometimes it'll drop off to the double digits (60 cfu/mL, 90 cfu/mL, etc.), and then it'll start spiking upwards (about 200-1000).
I have taken to rotating sanitizers within budget constraints--we primarily use a sodium hypochlorite-based sanitizer, but I switch it up 1 to 2 times a week with a PAA (peroxyacetic acid).
I have taken a couple samples of the rinse water, and can probably rule out it being a potential source of post-sanitizing contamination.
I will say that the equipment that is being tested every week is a fine stainless steel mesh and a steel surface with several hyper-thin grooves--so yes, I am concerned that we simply have an inaccessibility issue which is inhibiting our cleaning and sanitizing. We are as thorough as we can be (no way to break the equipment down further), and there are no visible signs of growth or anything "funky".
Any way for me to make sense of these readings, or recommendations for better sanitizer rotation? We were given recommended APC maximums by an outside consultant some time ago, to which I've tried my best to adhere. We've never yet used an iodine or ammonium based sanitizer; would either of those be potentially useful?