... passing impeller, then formed fine air bubbles with diameter from 5um---15um. Fine bubbles hold solid suspension in the water rising ... surface of the water, then formed scums, fine air bubbles will last 50~60 seconds in the water.IV. Cavitation ... Featuresl Large aeration volumel high speed rising of fine bubbles, fine bubbles, high densityl simple maintainance,lower power consumptionl little noise ...