Jim, there is a magnetic filter disc that goes between a ff filter and the filter mount. With some testing it might be a good idea, if space permits and the gunk can be delt with and it does not plug up.
On another thread I have described a test I'm going to do with a PurePower filter. Over the next comple of months there will be some photos, uoa's and analysis by Terry on a washable ss ff filter.'
I don't think there is any other way, on my budget to figure out if these filters work. This test is not science, just practical application with actual lab tests and photos. There are too many members here shooting from the hip. We'll let Terry Dyson have a few words, here, too.