Tilapia For Sale, Aquaponics Accessories and Complete Indoor Compact System askmilton.com I have 4″ PVC pipes cut at 5′ long the 1st 3 pipes I cut 6 3″ square openings, and i used water cups made openings with hot metal on the bottoms and sides, The last pipe i cut out 9 2″ openings for my small cups witch hold my newly sprouted seedling, At this time I have 4 tilapias and 5 goldfish