Smart ATO Micro 120P - Auto Top Off System

In stock

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Now Includes Siphon Break

One of the smallest all-inclusive auto top off systems on the market today. The Micro ATO includes an optical water level sensor to keep an eye on the level within the sump with no moving parts. The optical sensor is very reliable, even in complete darkness, keeping a steady water and salinity level replacing any evaporated water with fresh water. The Micro ATO, like its predecessor, uses a magnetic mounting solution that works for tanks and sumps that have up to 1/2" thick walls.


An auto top off system is one of the first automated devices any reef keeper should have. When water evaporates, the salt is left behind slowly increasing the salinity of the tank. By utilizing an ATO device evaporated water can easily be replenished by the top off unit throughout the day keeping your tank's salinity very stable. Most of the time the location where the sensors need to be placed can be very limited in space.


AutoAqua has released their Micro ATO system making it the smallest auto top off unit on the market today. The downfall for most top off systems is the float valve or moving parts. AutoAqua utilizes an optical sensor to visually look at the water level. With the magnetic mounting of the optical sensor placement options are limitless while if the magnets are ever to slip or the sensor gets knocked and moved, the Micro ATO provides a real-time fail safe protection against such instances.


The siphon break needs to be mounted higher than the water level, and within the ATO reservoir to function properly. Water dripping out the hole when the pump is on is normal.


Whats Included:

  • DC Feed Pump
  • Siphon Break
  • Controller
  • Optical Sensor
  • Power Adapter
  • Magnetic Sensor Mount
  • Tubing (8.5mm OD - 6.5mm ID)
  • Hang on Tubing Mount
  • 1 year warranty


Pump Specs:

  • DP-200 Brushless
  • 6.5 ft max head height
  • 74 GPH
  • 4.5w @ 12vDC
  • Cord Length 5ft
More Information
UPC 4714041211764
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Product Questions

Just curious if this product will work if I have a rain barrel beside my aquarium filled up with water will this product take the water from the rain barrel and place it into my aquarium when it goes off?
Question by: John on Jan 25, 2018, 6:19 PM
The Smart ATO will work in that fashion. The only thing you will need to consider is the head height that will be required to pump out of an almost empty barrel, and then also the output needs to be higher than the barrel to prevent a siphon from forming and emptying the entire barrel.
On another note, we do not recommend using rainwater for saltwater aquarium top off use. Rainwater carries many pollutants and other impurities that without filtration could cause undesired results.
Answer by: Charlie on Jan 25, 2018, 6:43 PM
Can I put the sensor in a main display tank if I use LED lights? Will LED lights interfere with the sensor ?
Question by: Tom on Apr 29, 2017, 9:30 PM
Hey there,
You can certainly use this ATO in your display. The sensor uses a small laser and prism and ambient light will not interfere with the unit's function.

Have a great day!
Answer by: Zack on May 3, 2017, 9:22 AM
Can you tell me how much water line drop this sensor gives you before it triggers the filling command? I want to see if it's more or less sensitive than my current ATO system
Question by: marc on Apr 25, 2017, 1:19 PM
Hey there,
These ATOs are actually pretty accurate/sensitive to any changes in water level. This ATO uses an optical sensor and a small prism to read the water level and we rarely see more than a small fraction of an inch (perhaps 1/8" to 1/4") before the pump kicks on.

Hope this helps!
Answer by: Zack on Apr 28, 2017, 10:10 AM