Why Is My SUNSUN HW-304B Blowing Air Bubbles Into the Tank?
Exact model: SUNSUN HW-304B
Safety: Disconnect the relevant power source and isolate moving, hot or pressurized components before service.
A.
Start with the accessible checks
What this suggests: Air bubbles that fade after a first fill point to trapped air.
What to do
- With power disconnected, verify IN receives water from the tank and OUT returns it, keep the intake submerged and the canister below tank level, and fill the canister to the recommended level.
- Prime with the blue button until an unbroken water column forms; do not dry-run the motor.
Still not fixed? Continue to the next check.
↑ Back to the repair pathsB.
If the problem remains after the first checks
What this suggests: Bubbles that continue after the filter is fully primed indicate suction-side air entering at the inlet strainer, tubing or tap-block seals.
What to do
- For persistent bubbles, remove and clean the tap-block seats, inspect both small O-rings and the inlet hose for cracks, and replace damaged, correctly sized seals or hose.
- Re-prime and release remaining trapped air with the canister upright.
Confirm the repair
A sustained bubble-free return and steady pump sound confirms the fault is corrected. The first-fill air-release method is documented; exact replacement-seal dimensions depend on the fitted head revision.