A robotic pool cleaner that bobs on the surface instead of sinking to work is frustrating, but the cause is almost always simple: trapped air.
Burp the Air Out First
When you drop a robot straight into the pool, air gets sealed inside the impeller housing and filter chamber, making the unit buoyant. The fix is to lower it into the water on its side and gently rock or tilt it until you stop seeing bubbles rise. Once the air is out, the robot settles to the bottom and its suction and weight keep it planted.
Check the Filter and Lid
A filter lid or access door that is not fully latched can also hold an air pocket. Make sure the filter compartment is seated correctly and closed completely. A cracked housing or worn seal can trap air too — inspect for damage and replace worn parts from our parts page.
Buoyant Cord and Old Foam
Some cleaners have flotation built into the cord to keep it off the pool floor. If your robot itself keeps floating even after burping, the internal foam or float can become waterlogged or, conversely, the unit may simply be too light. Heavier, well-engineered corded robots like the Dolphin Sigma sink and stay put reliably. If floating is a recurring battle, see our best robotic pool cleaners picks for models that grip the floor with confidence.
