A robot pool cleaner that floats instead of sinking usually has air trapped inside its body or a worn, waterlogged float or filter: purge the trapped air by lowering it into the water slowly and on an angle, and check the filter, floats, and seals for wear.
Why a cleaner floats instead of sinking
- Trapped air. Air pockets sealed inside the housing or filter chamber keep the unit buoyant until they are released.
- A waterlogged or degraded float. Many cleaners use internal foam floats or buoyancy chambers to control descent, and these can shift, crack, or absorb water over time.
- A clogged or saturated filter. A filter packed with fine debris can change how the unit settles and hold air against the media.
- Loose or aged seals. Worn gaskets or a poorly seated lid can let air stay inside where water should displace it.
- Wrong entry method. Dropping the cleaner in flat, on its back, or too fast traps air that a slower entry would push out.
Steps to get it to sink
- Lower it in slowly and on an angle. Hold the unit at roughly forty-five degrees and submerge it gently so air escapes as water enters. Tilt it side to side under the surface until bubbles stop.
- Open and drain the filter chamber. Remove the filter or canister, empty any debris, and let water fully replace trapped air before reseating it.
- Inspect the floats and buoyancy parts. Look for cracked foam, water inside a sealed chamber, or a float that has come loose. Replace worn floats with the correct part for your model.
- Check the lid and seals. Confirm the cover is seated evenly and gaskets are intact. Reseat or replace any seal that looks flattened or torn.
- Retest in the water. Resubmerge and watch whether the unit settles to the floor and begins to grip. Repeat the angled entry if it still rides high.
When it is the cleaner, not the pool
Some floating points to an internal fault rather than technique. Signs include water pooling inside the sealed motor or battery housing after use, a buoyancy chamber that fills faster each session, or a unit that will not sink even after the filter is clear and the air is purged. A cracked housing that lets water into places it should never reach is a hardware failure, not a setup issue.
If your cleaner keeps floating after these checks, log the pattern and compare it against known model behavior on the Tracker, and review how descent and floor contact fit into overall capability on our robot pool cleaner autonomy page.