Interestingly enough, Tunze was one of the first manufacturers to produce a reliable automatic freshwater replenishment device for aquaria - an endeavor that began in 1985. Since then, the Osmolator (osmotic regulator) has proved to be the most reliable and widely used ATO system for saltwater aquariums. It features built-in fail-safes and includes all of the components you need, short a constant supply of fresh RO/DI water. Needless to say, when we got wind of the Osmolator 3 way back in 2021, we were eager to see what kind of improvements could be made to an already very successful device. 

Tunze Osmolator 3 Components
Tunze Osmolator Optical Sensor

New Compact Optical Sensor

The biggest design shift in this new Osmolator is centered around the compact all-in-one optical sensor. They have completely done away with a central control box and this tiny optical sensor is now what houses all of the circuitry that governs the control of the osmolator. The large, precise optical sensor detects the water level with an accuracy of 0.5mm and is resistant to air bubbles, deposits, and scratches. The independent thermal safety sensor stops the ATO pump in the event of overfilling. The strong magnetic mount makes it incredibly versatile and the included protection cap will prevent critters from interfering with the ATO operation. 

Tunze Turbelle High Jet Osmolator Pump

New Turbelle High-Jet Pump

With a maximum delivery head height of 20.3 ft, the Turbelle High Jet is designed to handle even the most demanding uses. It is thermally designed for external operation but can also be fully submerged. The ½ inch thread on the suction side and ¼ inch thread on the pressure side make it highly compatible with whatever your plumbing situation demands. The built-in dry-run and blockage protection help ensure long-lasting performance and it operates using safe low-voltage 12V DC electricity. 

What's in the box

  • Osmolator 3 Sensor
  • Magnet Holder
  • Turbelle High Jet Pump
  • 12V DC Power Supply
  • Tube and Tube Holder


  • Plug-n-Play
  • Compact AIO design
  • Max. Glass Thickness (Sensor): 15mm (0.59")
  • Max. Glass Thickness (Tube Holder): 22mm (0.87")
  • Max. Delivery Height: 6.2m (20.34')