Best Auto Top Off Systems of 2022
ATO systems are so incredibly useful for a saltwater aquarium because they automate the most mundane maintenance task of replenishing the aquarium with freshwater lost to evaporation. This not only means you can hold a constant water level but you will also see a much more stable salinity level. Having reliable components from a brand you can trust is all that much more important when automating something as critical as your tank's salinity and water level.
While all ATO systems will fail at some point or another, what happens after that failure is where it counts. Does the ATO system have redundant sensors or logic in place that protects your tank from being overfilled? Does it notify you when the freshwater reservoir is empty or have something in place to protect the ATO pump from running dry? These are the kind of protections that make a reliable ATO system and features you see on our list of Best ATO systems of 2022.
Neptune Systems ATK V2 Auto Top Off Kit
Neptune Systems ATK is the only ATO system with three layers of protection, two types of sensors, and built-in logic that all work to protect your aquarium against ATO failures. When integrated into your Neptune Systems Apex, the level of monitoring and control becomes even more robust with additional water sensors and control via Apex Fusion.
Even if you don't utilize a Neptune Systems Apex Controller, the ATK works as a standalone ATO device and has some great benefits including redundant optical sensors to monitor water level plus a mechanical float valve as an emergency overfill protection.
In addition to the triple-redundant water level control, the FMM module has built-in logic that "learns" the average fill times for your aquarium and limits the pump fills as an added layer of protection against overfills and floods.
Tunze Osmolator Universal 3155
What more can we say about the Tunze Osmolator 3155 at this point? It is one of the most reliable and best-selling ATO systems on the market and has held the top spot for the last 15-20 years.
The Osmolator 3155 was the first ATO to integrate both an optical sensor and mechanical float switch to create redundant water level controls for extra protection against overfills. It is also programmed with a maximum 10-minute pump run time and features an adjustable pump speed so you can accommodate different-sized aquariums.
The controller itself has indicator LEDs so you can see the status of your ATO system at a glance and it even tells you when the pump is running to make it easy to monitor the function of your water level sensors. The built-in audible alarm will notify you during a dry run scenario in the reservoir or when the high-level float has been triggered indicating an overfill.
Reef Breeders Prism Auto Top Off
Reef Breeders Prism Auto Top Off is our favorite compact ATO that works great in AIO-style aquariums but also functions in aquariums with traditional sumps up to about 75 gallons in total water volume.
The one-piece water level monitoring device contains three infrared sensors that provide dual protection against overfills. Everything is built right into the sensor itself so there are no additional controllers or extra floats/wires to deal with making it super easy to install. The included pump is ultra-tiny measuring only 1.25" wide which means you can drop it right into a classic 2.5 - 5 gallon carboy without problems and it can deliver water up to 8 ft vertically.