Water Tech Blue Sapphire Robotic Pool Cleaner The Blue Sapphire is the perfect companion for any large pool; most large pools can be cleaned in as little as two hours Made of the highest quality parts including the industrys best chemical and algae resistant PolyVinyl Alcohol (PVA) brushes Its state of the art obstacle sensor will prevent the machine from getting stuck on ladders or other obstructions in the pool Included with the unit is an internal, reusable microfilter bag that removes debris as small as two microns, keeping your pool free of sand, silt, algae as well as larger debris like leaves and gravel Unique control panel communicates directly with the robot, which gives you the option to program the time or work in default mode choosing the time parameters