Famfu mai datti na ruwa ya bambanta da famfo mai tsafta saboda ruwan yana iya ɗaukar yashi, ƙananan duwatsu, zaruruwa ko sludge. Masu saye yakamata su fara rubuta magudanar ruwa, kai, ƙaƙƙarfan kaso da girman barbashi mafi girma. Idan famfo don aikin najasa ne, ƙayyadaddun samfuran suna nuna nau'in famfo nau'in WQ tare da girman fitarwa na 50-600 mm, 10-7000 m³ / h kwarara da 5-60 m kai, dangane da ƙirar.
Hakanan yana da amfani a tambayi yadda za a shigar da famfo. Wasu rukunin yanar gizon suna buƙatar famfo mai nutsewa tare da titin jagora, yayin da wasu sun fi son famfun laka a kwance wanda za'a iya buɗewa don duba lalacewa. Kyakkyawan sayan ba kawai game da jikin famfo ba. Abubuwan da aka gyara, ruwan hatimi, tsayin kebul da samun damar sabis ya kamata a duba kafin a ba da odar, don haka rukunin yanar gizon baya rasa lokaci yayin farawa{3}} sama.
