Abstract: The invention provides a modular frame for mounting at least one magnet apparatus in a fluid receptacle, a kit of parts for forming the modular frame, a system for removing ferrous particles from a fluid receptacle, and methods of use. The modular frame comprises first and second engagement members for engaging the frame with a wall of the fluid receptacle, and at least one coupling member for coupling the magnet apparatus to the frame. The magnet apparatus is mountable in the fluid receptacle to attract and remove ferrous or magnetically attractable particles from a fluid volume in the fluid receptacle. The first and second engagement members are respectively removably connected to the at least one coupling member. The modular frame may be assembled from a kit of standardised components to fit a particular fluid receptacle, and may be disassembled or reconfigured according to requirements.