Xaalado kala duwan ayaa la heli karaa, oo ku habboon nidaamyada kala duwan ee shaandhaynta, sida shaandhada hoose, shaandhada dambe, shaandhaynta dhinaca, filtarka sare, qulqulka qulqulka, shaandhada dibadda, baaldiga shaandhada iyo hababka kale ee sifaynta ayaa la isticmaali karaa.