A fluid recirculation and makeup supply system having an alternate purification loop (84) in parallel with a portion of the recirculation loop (26). In the alternate purification mode of operation of the system a predetermined portion of the recirculated fluid is drawn through the purification loop (84) in parallel with a flow of the remainder of the recirculated fluid through the normal parallel recirculation flow path (86). The volume of fluid drawn through the purification path (84) is established to maintain the purification loop operating at its maximum efficiency. A makeup fluid supply loop (24) having a normal flow path (42) and an alternate, parallel filtration flow path (50), communicates with the recirculation loop (26). The amount of fluid inputted to the makeup loop (24), supplied through the makeup loop (24) to the recirculation loop (26), and drawn through the filtration path (50) are controlled, in the alternate filtration mode of operation, to establish a counter flow of fluid in the normal makeup flow path (42) so that none of the makeup fluid supplied to the recirculation loop (26) bypasses the filtration path (50).