Neptune Systems MOS Magnetic Optical Sensor

Neptune Systems MOS Magnetic Optical Sensor – compact mos magnetic optical sensor for Apex systems

The Neptune Systems MOS Magnetic Optical Sensor delivers precise water level monitoring with a modern, compact body. This magnetic optical sensor integrates cleanly with Neptune Systems controllers and fits naturally under Automate & Monitor.

How the Neptune Systems MOS Magnetic Optical Sensor works

This mos magnetic optical sensor uses reflected infrared light to detect wet or dry states in seconds. It replaces the OS-1 optical sensor and improves sealing against splashes. Place it in Controllers, ATOs, then track status under Water Level, Switches for fast visibility.

• Fully sealed, waterproof sensor body

• Strong magnetic mount with silicone-encased exterior

• Stable hold on glass or acrylic up to 1/2 inch thick

• Slim profile for cramped sumps and AIO chambers

• Rapid wet/dry change detection for accurate alerts

• Plugs into an Apex FMM port without extra wiring

Install in minutes: mounting and placement for the MOS

Mount the internal sensor and external magnet on opposite sides of the wall. The magnetic pair holds firmly on panels up to 1/2 inch thick. Meanwhile, the sensor also fits reservoirs with wall thickness up to 1/4 inch.

Where the Neptune Systems MOS Magnetic Optical Sensor excels

• Build a reliable ATO with Apex control

• Add a high-water alarm in your sump

• Track reservoir levels for dosing or AWC

• Safeguard against skimmer cup overflows

• Create service modes that pause equipment

Neptune Systems MOS Magnetic Optical Sensor specifications

• Mounting: Magnetic, silicone-encased external magnet

• Panel compatibility: Up to 1/2 inch glass or acrylic

• Reservoir wall guidance: Up to 1/4 inch thickness

• Connection: Apex FMM port

• Orientation: Vertical mounting recommended

• Replacement for: OS-1 Optical Sensor

What’s included

• MOS Magnetic Optical Sensor

• Internal sensor body with cable

• External silicone-encased magnet mount

• Quick-start guide

Frequently Asked Questions about the Neptune Systems MOS Magnetic Optical Sensor

Does the MOS work in both saltwater and freshwater?
Yes. The optical method works the same in either environment.

Can I use it outside the sump?
Yes. Mount it on ATO reservoirs, mixing containers, or skimmer sections.

How does it connect to Apex?
Plug the sensor lead into an Apex FMM port and assign the input.

Is it only for ATO automation?
No. Use it for high-water alerts, reservoir low-level warnings, and skimmer safety.

How tight is the seal against splashes?
The updated housing resists water incursion better than the OS-1 design.

Will the magnet scratch my tank?
The external magnet sits in a silicone sleeve to protect panels during placement.

 Follow the Reefing Buzz

• Reef tank updates in real time on Instagram

• Educational clips and tips on TikTok
• Stay updated on Neptune Systems on our Facebook timeline
• Share your setup and reefing experience on Reef2Reef