COARSE FILTER: The coarse filter must be installed such that it is easily accessible for maintenance work and can be inspected as per the maintenance overview. A coarse filter with mesh size from 50 - 67 micron (0.0019 in. up to 0.0026 in.) must be provided in the supply line between the tank and the fuel pumps. This filter must be sufficient to prevent complete blockage between maintenance intervals.
The course filter we installed in our 912iS Zenith CH750 (https://www.rotax-owner.com/en/videos-topmenu/builder/zenith-builder-series) is the AndAir gascolator GAS375-MF-62M with a course filter screen of 62 microns https://www.andair.co.uk/category/gascolators/
Make sure the S/N of your fuel pumps is not within the latest fuel pump S/B https://legacy.rotaxowner.com/si_tb_info/serviceb/sb-912i-013.pdf
The symptoms, you are describing (loud noise) were part of the issues with the affected fuel pumps.
