N-Fill Smart Auto Top Off System

Affordable & Reliable Auto Top Off System

• Redundant, Dual Float Sensors
• Smart Over-Fill Protection Built-In
• Intuitive Controller w/ Status Indicator LEDs
• Ideal for Nano to Mid-Size Tanks
• Safe for Freshwater or Saltwater Aquariums

The N-Fill Auto Top Off (ATO) is a simple, affordable system built specifically for nano to mid-size aquariums. Using dual float sensors and smart overfill protection, it automatically replaces evaporated water with fresh RO/DI so your tank's salinity stays stable day after day. The compact controller, clear status LEDs, and easy setup make it approachable for beginner hobbyists, while still being an ATO experienced reefkeepers can trust. By keeping the water level consistent, the N-Fill helps to reduce stress on fish and corals, improve overall tank stability, and eliminate the need for daily manual top-offs.

Dual Float Sensors

Two independent float switches monitor the same water line. The controller starts a refill whenever either sensor detects low water. Even if one sensor fails, the other still triggers top-offs. This redundancy helps prevent missed refills and provides an extra layer of stability compared to most ATOs on the market.

Smart Overfill Protection

If the pump runs for more than about 90 seconds, the controller pauses filling and triggers an audible alarm with a red status LED. This fail-safe helps prevent overfilling if a float sticks low, flow is restricted, or the reservoir behaves unexpectedly.

Simple On-Board Control Buttons

• Manual: Hold to run the pump for priming or quick refills, release to stop.
• Pause: Press once for a 30-minute pause. Ideal for feeding or light maintenance.
• Stop: Press once to disable automatic filling during major maintenance. Resumes after 24 hours.

LED Status Indicators

• Power: Controller has power and is ready.
• Filling: ATO pump is actively running.
• Status: Off during normal operation, blinking when paused, and solid red during stop mode or overfill alarm

Specifications

• Power Input: AC 100–240 V, 50/60 Hz
• Power Output: DC 12V 1A, UL Listed Adapter
• Maximum Pump Head: 160 cm | 63"
• Maximum Flow Rate: 180 L/h | 47.6 GPH
• Maximum Glass Thickness: Up to 15 mm | 0.6"
• Sensor Adjustment Range: Up to 10 cm | 4" Below Tank Rim
• Tank Compatibility: Freshwater and Saltwater Aquariums
• Control Modes: Manual Fill, 30-Minute Pause, 24-Hour Stop
• Over-Fill Protection: Auto Timeout After ~90 Seconds with Alarm and Status LED
• LED Indicators: Power, Filling, Status

What's Included?

N-Fill Controller

Dual Float Sensors with Adjustable Holder

N-Neon ATO Tubing Organizer

Submersible DC Pump

Water Tubing (2 M | 6.5 ft)

Siphon Breaker Connector with Cover

UL Listed 12V 1A Power Adapter