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Dwarf Angelfish
Neptune Systems Optical Level Sensor with Magnet Mount

Please Note: Return of electrical equipment for exchange or store credit is limited to 30 days from the date of purchase. Beyond 30 days, please contact the manufacturer for repair or replacement as covered by the manufacturer's warranty.

Returned products must be unopened and in the original packaging to receive full store credit. Products that have been opened, used, or lightly used, will incur a 15% processing fee. Upon receipt of the returned product, store credit will be applied, minus the processing fee.



* Optical aquarium water level sensor for Neptune Apex FMM Fluid Monitoring Module
* Sensor detects changes from being wet to dry or dry to wet and signals your Apex FMM
* Use with your aquarium ATO (auto-top-off), as a high water level sensor in your sump, and much more

Experience reliability and peace of mind with the FMM-compatible Neptune Systems Optical Level Sensor with Magnet Mount.

There are many useful purposes for water-level sensors on an aquarium. They can help you build an auto-top-off, monitor the levels in your supplement containers, even help automate saltwater mixing containers. The solid-state, optically-controlled sensors are reliable and dependable. The sensors work by using LED emitters and receptor in clear enclosure such that when it becomes wet, the light bends and no longer completes the circuit.

The Neptune Systems Optical Level Sensor with Magnet Mount plugs into your Neptune FMM and, using reflected infrared light, will signal your Apex when it changes state from being wet to dry or dry to wet. This sensor can be used for constructing your own ATO (auto-top-off), as a high-level warning sensor in your sump, water storage level sensor, and much more. The sensors can be mounted into custom brackets or through a hole in a vessel. Included are a fastening nut and silicone washer. The sensors can be mounted on any type of reservoir that has up to 1/4" thick walls. These sensors are sold individually.

What's Included?

  • 1x OS-1 Optical Sensor with nut and washer
  • 1x OS-M Optical Sensor Magnetic Mount

Note: FMM Module required for use. Sold separately.

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