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Tunze Osmolator 3155 - Auto Top Off System

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Product Description

Tunze Osmolator 3155 - Auto Top Off System

The Tunze 3155 Osmolator is one of the best ATO systems in the aquarium hobby, and is trusted and used by almost all the best saltwater setups around.  Tunze's Osmolator is capable of almost any sized aquarium when topping of your evaporation water is essential and comes with everything needed to setup and use.  With high quality parts and strong magnets the Tunze 3155 is an amazing choice for your automatic top off system, and super simple to setup.

Water level regulation with static sensors are included

In 1983 already, TUNZE® Aquarientechnik introduced one of the first water level regulators to aquarism. Today’s generation of Osmolator contains a static and compact sensor with infrared technology, achieving an osmotic stability in fresh-water and marine aquariums through a precise, regular and safe compensation of the evaporated water. The Osmolator 3155 comprises a controller, two sensors, two magnet holders for sensors and numerous accessories. It is suitable for use in cabinet filter plants, in Comline filters or directly on the edge of the aquarium.

An infra-red operated mini sensor recognises the water level precisely.

A second safety sensor permits a reliable functional control.

The 5017 protects the metering pump against running dry or reports an empty storage tank.

The 5017 displays all functions optically and sounds a signal in case of failures.


The Osmolator is operated on 11 V safety extra-low voltage.


Product Reviews

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  1. Tunze 3155 King of ATO

    Posted by Shooter McDabn on Apr 20th 2020

    The Tunze 3155 ATO has been my goto auto top off for over 10 years. This unit never fails and keeps a stable water level. The pump+hose+ Complete install hardware is included. All you need is a reservoir to hold your water. Quality company, quality product. Buy the best, buy once.

  2. Best ATO

    Posted by William Schroeder on Feb 10th 2020

    Okay, when you buy this, there's a lot of parts in tiny box and the directions are a bit confusing. Just go to YouTube and search up a video on how to set it up. It's way easier than the directions lead you to believe. Once it's up and running it works like a champ.


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