in low volume magnetic treatment of water a single core unit includes an outer casing 62 made of non magnetic material such as copper and fittings 64 and 66 made of non magnetic materials such as brass for purposes of the present description 34 non magnetic 34 means materials having a very low magnetic permeability and virtually no ferromagnetic characteristics such as copper brass pvc nylon and delrin for example 34 magnetic 34 materials are those exhibiting high magnetic permeability such as iron and steel in one embodiment inner casing 68 is a threaded galvanized 1 2 inch steel pipe with an inner diameter of approximately 0 633 inches casing 68 is made of a ferromagnetic material having a high magnetic permeability such as preferably galvanized iron or steel although other materials may be used inner casing 68 has an outside diameter less than the inside diameter of outer casing 62 and is uniformly spaced therefrom by threaded attachment to fittings 64 and 66 positioned within inner casing 68 is a tube 70 of non magnetic material such as copper which is open at both ends and has a pair of apertures 72 74 and 76 78 therein tube 70 within inner casing 68 forms an annular chamber 79 apertures 72 and 74 are transversely aligned along an axis which is rotated 90 u00b0 from the axis along which the apertures 76 and 78 are aligned this causes the water which enters one end of unit 60 to make a 90 u00b0 turn upon the longitudinal axis before it exits from the opposite end.