Abstract: A cleaning process using aqueous liquid compositions for cleaning membrane filters used primarily in tubular backpulse liquid filtration systems in Kraft pulp mills for white liquor, green liquor and lime mud filtration and in chlor-alkali processing. The process removes silicate and aluminosilicate materials that reduce filtration efficiency with minimal damage to the membrane filter. The method consists of a first stage first liquid composition flush to remove soluble calcium compounds followed by a second stage second liquid composition flush that dissolves the silicate and aluminosilicate compounds and prevents reprecipitation of dissolved aluminum and silicon compounds in the filter membrane. The filters are then flushed by water.