Aquaponics Sludge Separator

This is my design for a separator for use in an aquaponics system for the effluent from the fishtank before sending the water to the grow beds. The system is similar to a septic tank except that it uses aeration to prevent ammonia formation from additional decomposing of the sludge (in principal). I am intending on using a unit about 24cm x 36cm to handle the water from a 250gallon fish tank next summer. The small tubes are the aerator tubes. The large tubes are 1" PVC (with holes) to be used to drain collected sludge. Sets of tubes will be connected. This can be built with acrylic, or in rubbermaid tubs or even (for commercial sized uses) in waterproofed outdoor garden bench storage units.