Abstract: A filtration system, especially for use in aquaria has a lower or first chamber, a middle or second chamber and an upper or third chamber with an interconnecting valve to provide fluid communication therebetween. A microfilter is disposed between the first and second chambers. The upper or third chamber may be divided into two separate parts; one of which parts forms a gravel filter, and the other of which parts forms a pump conduit between the valve and an outlet of the system for connection to a suction pump. Alternatively, a separate pump conduit may be used.