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Neptune Optical Sensor w/ Magnetic Mount for Apex FMM

Neptune Optical Sensor w/ Magnetic Mount for Apex FMM


Item #: NS17297

In Stock

Neptune Systems OS-1-M Optical Level Sensor with Magnetic Mount

This sensor plugs into the Neptune Systems Apex FMM (Flow Monitoring Module) 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, silicone washer and magnetic mount. These sensors are sold individually. 


  • Cable length: 10 feet / 3m
  • Hole size: 9/16" / 15mm

What`s Included?

1x OS-1 Optical Level Water Sensor

1x OS-M Optical Sensor Magnetic Mount

NOTE: Neptune Systems Apex Controller and FMM Module required and sold separately.

Manufacturer information

Neptune Systems Aquarium Supplies
Neptune Systems is one of the world’s leading manufacturers of aquarium controllers. The company was founded in 1995 for the purpose of developing affordable water quality monitoring and control instrumentation. Their engineering team has extensive expertise in computer hardware and software system design as well as a background in water quality analysis. Neptune Systems uses these finely-honed engineering skills to develop innovative monitoring and control solutions for use in reef and fresh water aquariums, aquaculture tanks, hydroponics systems and general laboratory use. Neptune Systems is best known for their AquaController line. The company is known for their innovation and customer centricity.

4 Stars


Reviewed on
January 24, 2020

Yes, I would recommend this.

Great for safety!

Pros: Great for water level monitoring.

Cons: Not good if it near turbulent water as splashes will false trigger

I use these in various places to act as a notification and kill-switch for anything that might overflow.

Was this review helpful? 2 0


Reviewed on
March 07, 2019

Yes, I would recommend this.

Works as expected

Pros: Magnetic

Cons: None

Works as expected. Easy to adjust height due to the magnet

Was this review helpful? 1 0


Reviewed on
August 20, 2018

Yes, I would recommend this.

Accurate and multi purpose

Pros: Accurate. Low profile

I picked one of these up to be able to monitor my ato res level and it works great. Very accurate and easy to program in the apex. The bracket works well but not as nice and the probe or ATK brackets

Was this review helpful? 2 0


Reviewed on
September 19, 2017

Yes, I would recommend this.

Nice little gadget.

Pros: Compact

Cons: None

Nice little addition to your FMM. I use it for my ATO low level sensing.

Was this review helpful? 0 1


Reviewed on
August 21, 2017

Yes, I would recommend this.

Works as designed and reliable

Pros: Accuracy

Cons: None

Very nice sensor and accurate. I have several of these in use and have not had any issues whatsoever.

Was this review helpful? 3 0