HARDWARE
Component & part identification
Relevant assemblies
Impeller, rotor shaft, hoses, O-ring, UV assembly.
Exact replacement part numbers are not displayed until documented compatibility is confirmed.AQUARIUM FILTERS · MODEL PROFILE
SUNSUN HW-304B
External aquarium canister filter. Canister filtration system. Manuals are shared across several HW models; replacement-part interchangeability must be checked.
MODEL TROUBLESHOOTING
Start with the symptom, then follow the checks
This information comes from a shared HW-series reference; check the UV module, rotor and electrical rating fitted to your HW-304B.
Before starting: Disconnect the filter from power before opening the housing. Never look at an exposed, operating UV-C bulb.
Why isn't the UV light on my SUNSUN HW-304B turning on?
Do not look directly at an operating UV-C bulb. With power disconnected, verify bulb seating and the exact replacement rating.
Get step-by-step checks and outcomes →Why is my SUNSUN HW-304B barely pumping any water?Check the easiest restrictions in order: hoses, media, fittings, then the impeller.
Get step-by-step checks and outcomes →Why is my SUNSUN HW-304B making a rattling noise?First distinguish trapped air from a damaged impeller. Gurgling that clears after priming is not the same as a persistent hard rattle.
Get step-by-step checks and outcomes →Why won't my SUNSUN HW-304B filter motor start?Separate an electrical power failure from a jammed or damaged rotor before replacing the motor.
Get step-by-step checks and outcomes →Other symptoms recorded in the source manuals
Additional fault causes and service notes are retained in the research database. The four guides on this model page are the starting points with detailed checks and result-based actions; other issues will be published after model-specific technical verification.