I went out for my first loads of the year today and had a heck of a time with nozzles plugging.  Upon further inspection I found that it was little rust particles causing the problem and I found a few of them in the base of my filter.  Its an 80 mesh filter.  My question is how they are getting past the filter?  Last summer I put a new filter in and the dealer said the new ones don't use o-rings on the top and bottom.  Is the filter supposed to snap in firm?  Do I need a gasket on the bottom of the filter canister?  It's  Bestway Field Pro IV.