One or two fluids (usually filtered air and water, see section filtration) are always used in upflow mode to wash filters, except in special cases (filtering media that is lighter than water ... Filtration, Aquazur, Filtrazur, Filters, Mediazur, Seaclean ... Filtration Aquazur Filtrazur Filters Mediazur Seaclean ... filter washes ... Filters...