Morning,
     
 
i have  both the 10 and 20,   so  cant see the 30 been any diffrint,    as mentiond in the previous post,    turn off,  turn the taps off,,  unscrew them,  then  unlock the blue catches,take a firm grip and  open,  then  just open  over a towel,   thies filters  can  be a bit stiff to open,    as for the  what ever you want to put in it,  just use a filter bag  or  equivalent,
    i have found them to be pretty good  and fairly quite as well!    
   just a spot of advice,   give the O ring a good clean when you clean the filter,     also  the pump  head   on the inside   has the 2 wholes,    take a grip and  give it a  anti clock wise turn  to get to the impleller and stuff!
   good luck