XP Aqua Duetto2 ATO System XP Aqua Duetto2 ATO System is a compact automatic top-off system for freshwater, saltwater, and reef aquariums. It uses a tiny dual-optical sensor, intelligent QST programming, and a included DC top-off pump to help keep aquarium or sump water level stable while reducing the risk of overfilling. XP Aqua Duetto2 for Precise Aquarium Auto Top-Off Stable water level is especially important in reef aquariums because evaporation removes freshwater while leaving salt behind. The Duetto2 automatically replaces evaporated freshwater from a separate reservoir, helping maintain more consistent salinity, sump level, return pump operation, and equipment performance between manual refills. Dual Optical Sensor ATO Protection Features Dual-optical sensor design: Two precise optical level sensors are packed into one very small sensor body for compact installation. Two layers of overfill protection: The primary sensor maintains water level while the secondary optical sensor provides added protection. Intelligent QST programming: Built-in controller logic works with the sensors to help prevent overfilling. Plug-and-play setup: No programming or manual adjustment is required for normal operation. Works in darkness: Optical sensing does not require aquarium lighting to function. Magnetic sensor mount: The sensor can be mounted and adjusted easily on suitable aquarium or sump glass. Small installation footprint: The compact sensor is useful in sumps, rear chambers, and tight ATO sensor locations. Freshwater top-off stability: Helps reduce salinity swings caused by evaporation in marine and reef systems. Duetto2 Pump and Mounting Specifications Product type: Automatic top-off system Application: Freshwater, saltwater, reef, sump, and rear-chamber top-off control Power input: 100-240 VAC, 50-60 Hz Included pump: XP Aqua ATO DC pump Pump flow rate: 74 gph / 280 lph Pump maximum head: 8.2 ft / 250 cm Maximum mounting thickness: 1/2" / 12.7 mm Sensor type: Dual optical water level sensor Control type: Preset automatic operation with no user programming required Reservoir: Freshwater reservoir sold separately Duetto2 Aquarium Installation Planning Notes Best installation point: Place the sensor where water level changes from evaporation are consistent, such as a return pump chamber or stable rear filtration chamber. Reservoir sizing: Use a clean freshwater reservoir sized for the aquarium's normal evaporation rate without creating excessive risk if misconfigured. Anti-siphon setup: Route the top-off line and siphon break correctly so freshwater cannot continue siphoning after the pump stops. Sensor cleanliness: Keep the optical sensor free of algae, film, salt creep, bubbles, and debris for reliable operation. Return chamber safety: Avoid placing the sensor in turbulent areas where bubbles or splashing can cause unstable readings. XP Aqua Duetto2 Setup Directions Choose a stable water-level location in the aquarium, sump, or rear chamber where evaporation causes the water level to drop predictably. Mount the dual optical sensor with the magnetic holder on clean glass within the supported thickness range. Place the ATO pump in a clean freshwater reservoir. Route the top-off tubing to the aquarium or sump and secure the outlet so it cannot move, fall out, or siphon unintentionally. Install the siphon break according to the XP Aqua instructions and confirm it is positioned correctly. Connect the pump, sensor, controller, and power supply according to the manual. Test several top-off cycles before leaving the system unattended. Inspect the sensor, pump, tubing, siphon break, and reservoir during regular maintenance. What's Included XP Aqua Duetto2 controller with dual-optical sensor Magnetic sensor mount ATO DC pump Power supply Top-off tubing Siphon break
