Neptune Systems ATK V2 Auto Top Off Kit

Keep your tank topped off automatically. The Neptune Systems ATK V2 replaces water lost to evaporation to hold a rock-steady water level, preventing the salinity swings that stress fish and corals. It runs completely standalone right out of the box, and it plugs straight into an Apex controller when you want app monitoring and alerts. Explore more reef equipment and controllers.

Reliable, Redundant Level Control

The ATK V2 uses two optical sensors with no moving parts to read your water level, backed by a mechanical float valve as a fail-safe. Its IQ-Fill run-time intelligence learns how long a normal top-off should take and shuts the pump off if something is out of range, so it will not overfill your tank. Audible alarms let you know the moment attention is needed.

Standalone or Apex-Connected

Use it on its own with no controller required, or connect the included FMM module to an Apex system to monitor levels, log usage, and get alerts through Apex Fusion and Mobius. Either way, the included 24V DC PMUP pump delivers quiet, dependable top-off from your reservoir.

Features

• Automatic top-off that prevents salinity and water-level fluctuations
• Two optical sensors with no moving parts for precise readings
• Mechanical float valve fail-safe plus audible alarms
• IQ-Fill run-time intelligence guards against overfilling
• Included 24V DC PMUP pump for quiet, plug-and-play operation
• Works fully standalone, or connect to an Apex controller via the included FMM module
• Comes with mounting hardware and tubing for a quick install

What's Included

• ATK V2 sensor holder with dual optical sensors and float valve
• 24V DC PMUP pump
• FMM (Fluid Monitoring Module)
• Mounting brackets and hardware
• Tubing and power supply

Specifications

Recommended Pairings

• A Neptune Apex controller to unlock monitoring, logging, and alerts
• An RO/DI or top-off reservoir for a clean freshwater source
• More reef and marine equipment

Frequently Asked Questions

Do I need an Apex controller to use it?
No. The ATK V2 runs completely standalone. An Apex just adds remote monitoring, logging, and alerts through the included FMM module.

How does it prevent overfilling?
It combines dual optical sensors, a mechanical float valve fail-safe, and IQ-Fill run-time intelligence that shuts the pump off if a top-off runs longer than normal.

Does it come with a pump?
Yes. A 24V DC PMUP pump, sensors, FMM module, mounting hardware, and tubing are all included.

Can I use it on a freshwater tank?
Yes. While it is most popular on reef tanks, it works on freshwater aquariums too.