So I got my ATI water results back and Zinc, Nickel, and Iron were high. Went looking at MP40s and found one to have a small amount around the end of the shaft, so I felt pretty good about finding the issue. While cleaning the sump out today as the detritus was building in the refuge section, cheato needed trimming, and figured a larger than normal water change was in order with the metals in the water from my analysis. I pulled everything out and figured I would pull the small powerhead out that churns the cheato to clean any debris from the impeller assembly. I didn't check this one once I found the rust in the MP40 shaft assembly....WOW was I surprised to find the whole impeller assembly full of RUST. I have only been using this powerhead for 3-4 months tops! It was an Aquatop PH-8.