It soes sound like you have disconnected a pipe somewhere and connected back to wrong fitting, just to clarify you only need to unscrew the large pre-filter holders ,remove old filters and replace,if you have waste water at 0.2 it shows your filter change was effective and will proably get lower with longer filter flush . I cant really think what you may have done other than somehow swapping waste/filter pipes which should not need to be touched on filter changes ,good luck with it