Weir Door Replacement
The Atlantic Water Gardens Biosys Skimmer+ and XL replacement flap assembly provides a new weir door mechanism for these Oase-compatible pond skimmer models. The flap assembly controls the water intake flow through the weir — when the flap warps, cracks, or loses its pivot, the skimmer's surface skimming efficiency drops and the water level inside the skimmer fluctuates erratically. This OEM replacement restores correct weir door function.
Weir Door Function and Skimmer Efficiency
The weir door flap on a pond skimmer serves a specific hydraulic function: it maintains a consistent head differential between the pond surface and the skimmer interior, which drives the surface flow that collects floating debris. A warped or broken flap disrupts this head differential, causing either too much bulk flow (bypassing surface skimming) or too little flow (reducing debris collection). The Biosys Skimmer+ flap assembly is precision-fitted to the skimmer housing dimensions to maintain the correct head differential across the full range of pump flow rates.
| Compatible Skimmers | Oase Biosys Skimmer+ and Biosys Skimmer XL |
|---|---|
| Component | Weir door / flap assembly |
| Function | Controls surface water intake flow and level in skimmer |
| Material | UV-resistant polymer |
| Part Type | Genuine Atlantic/Oase OEM |
How to Replace
Reduce pump flow or disconnect the pump before opening the skimmer. Access the weir door opening on the skimmer face. Remove the old flap assembly by releasing its pivot pins or clips as per the Biosys Skimmer service guide. Install the new flap assembly, ensuring pivot pins fully seat and the flap swings freely without binding. Restart the pump and confirm stable water level in the skimmer and correct surface skimming behaviour.
Ideal for maintaining Oase Biosys Skimmer+ and XL units in Canadian koi ponds and water gardens.