Distribution manifold for 5200gph sequence pump. Triple redundant to prevent back siphon overflow from sandbed-level output nozzles. Top to bottom: 1) first reverse mounted check valve that will open to allow air input and break siphon in event of power loss; 2) redundant reverse check valve; 3) primary return water line with forward-mounted check valve to prevent water back flow; 4) hose bib for attaching reverse-vacuum wand used to blow detritus off the rocks (imagine giant turkey baster with no need to squeeze the bulb).