Replacement Two Little Fishies Phosban Reactor 550, Soft 90 (PVC Elbow) Fitting, Part C. This part is also a replacement part for the PhosBan Reactor 150, though it's not listed on the Operation Instructions parts list. NOTE: The PhosBan Reactor 550 & 150 have two Soft 90 (PVC Elbow) Fittings. As pictured, there is only quantity one with each order.