When Atmann was supposedly going out of business maybe two years ago, where bubble magnus was using Atmans, they identified replacements. In fact BM also sold upgrade kits for those existing skimmers, which included new bubble plates along with the new pump. They had to do that because no other pump exactly fit in the place of the Atman. I know for my SWC160, that uses an Atman 2500, I was stuck with Atmans because SWC has done nothing to identify replacements. Now here's the strange thing.....Atman is still around. When the closing of the plant was announced, I purchased three backups, but now I see they are back on the market.
Did you purchase the Rock sp-1000 or did you stick with the Atman?
And FYI, this little trick has helped my Atman from stalling. Put 2 or 3 teflon washers (available at HD in hardware...in the drawers) on the impeller side of the shaft. I can only guess that opening up a slight space between the impeller and the face plate keeps the darn thing running.