Neptune ATK Auto Top-Off Kit - Version 2

The Neptune ATK Version 2 replaces water lost through evaporation using an automatic top-off pump and level-sensing assembly. It can operate on its own through the FMM module or become part of a compatible Apex aquarium-control system.

The design combines two optical sensors with a mechanical float-valve backup. Its IQ-Fill logic also monitors typical fill duration. These protections support the top-off routine, while the reservoir, tubing route and siphon-break installation still need to follow the setup instructions.

For a saltwater aquarium, fill the reservoir with appropriate fresh top-off water: evaporation removes water while leaving salt behind. Position the assembly where the system's evaporation-related level change occurs, and keep the sensors and float accessible for cleaning. Check the reservoir and actual fill behavior regularly after installation.