HEP Replacement Ballast for Aquatic Life 4-Lamp Hybrid Dimmable T5 HO lighting fixtures. When replacing a bad ballast, it is best to wait to disassemble and remove the bad ballast until the new ballast arrives and then swapping out will just take a few minutes. Item 470643. These ballasts can be used for other fixtures such as ATI, and retrofit kits. Wiring diagram is printed directly on the ballast.