Tunze Osmolator Nano 3152 Auto Top Off

Tunze Osmolator Nano 3152 ATO
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  • Tunze Osmolator Nano 3152 ATO
  • Tunze Osmolator Nano 3152 ATO Floats
  • Tunze Osmolator Nano 3152 ATO Pump
  • Tunze Osmolator Nano 3152 ATO Included Parts
  • Tunze Osmolator Nano 3152 ATO Magnets
  • Tunze Osmolator Nano 3152 ATO Power Supply
  • Tunze Osmolator Nano 3152 ATO Box

Tunze Osmolator Nano 3152 Auto Top Off

89% Recommend this to a friend (39 of 44)

SKU: 202331
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Quick Overview

The Tunze Osmolator Nano 3152 Auto Top Off is designed for smaller tanks, approximately 50 gallons and under. One of the safest ATO’s available. Utilizes an single sensor to monitor water levels and a controller that protects against overdosing. Magnetic holder for sensors up to 10mm or .39".

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Full Details

Introducing the little brother to the Tunze Osmolator, one of the industry’s most trusted automatic water top-off device and BRS Recommended. Designed specifically for smaller aquariums, roughly 50 gallons and under, the Osmolator Nano 3152 is a slimmed down version of the full sized 3155. It includes a processor-based anti-overfill system which turns the pump off if after five minutes of filling the level has still not been reached. The Osmolator Nano includes the control unit, low voltage (6V) pump, power adapter, 3m hose, magnet mount and protective cover.


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  • Good for a few months By Casey on 12/20/2014

    My second Ato has stopped working. When the unit works, it's great.
    When the first one stopped working, I reached out to BRS and Tunze. I learned that I was basically S.O.L without sending the unit back to them. I just decided to spend the money and buy a replacement.

    That was a workable plan for a few months until the second unit died on me. I've decided not to buy another. I'd rather pour the RO water in myself than purchase yet another unreliable model from BRS. I hope they find a more reliable nano ATO to promote.
  • Works well fills need By Thomas on 12/9/2014

    Bought this to top off my nano tank. Set up was easy and does a good job maintaining water level. Lot less hastle than topping of tank daily and keeps salinity more stable
  • Can't imagine how I lived without this thing By Sean on 12/4/2014

    No more lugging around jugs every other day, now it's only once every couple weeks! :) This is a huge upgrade and peace of mind. I have a small tank so this is huge in helping me keep my water parameters stabilized. This is a must-have for smaller reef tanks for people serious about their corals.
  • Works great By Meaton on 11/19/2014

    Perfect for my nano cube 28G reef tank
  • Compact. Works well. By Joseph on 10/29/2014

    The unit is very compact, works well, and maintains your water level with frequent small top offs.

    My only complaint is the pump doesn't have a suction or bracket so that it sticks to the bottom/side of your reservoir bucket.
  • Replaced Hydro-fill By peter on 10/7/2014

    I owned the IM Hydro-fill for about 6 months when the controller went out. I've only had the Tunze running for a couple of weeks but I like it better already. Triggers from slight water level drops and I like the idea of the built-in fail safe.
    Only complaint is the pump is pretty loud.
  • 14days Dead By Richard on 9/12/2014

    problem for the controller pump not working
  • Great System By John on 8/13/2014

    Works great with my 38 gallon
  • 14 months dead By Jason on 7/2/2014

    Dead after 14 months. pump is fine brain unit doesnt work anymore.
  • Great product very reasonably priced By Randy on 5/30/2014

    Love this little ATO system, and it's affordable for a Tunze product! I've had it for a week and it has been absolutely reliable with no fluctuation in my water level. My sump is a 10g aquarium with a heater, skimmer, and return pump all packed in, so it is a tight fit but it works. I left the cardboard separator between the two magnets because I had read that the magnets being too close can interfere with the float valve. It works like a charm and I couldn't be happier! Best $100 I have spent on my aquarium so far!
  • To the Top! By Taia on 5/21/2014

    Tunze has a great product here! It has been working flawlessly to keep my tank topped up and my levels much more stable. It's really one of the most essential pieces of equipment you can buy, it's well made, but my only gripe is the quick connect from the pump to the controller itself. I'd prefer something a bit more salt creep proof! But overall, I'll be buying another one for my next tank as well!
  • ATO for my nano By charles on 5/12/2014

    installed this ATO on my 28 gal.nano cube.so far it's working great.now my cheap protein skimmer works a lot better because of the constant water level.pump's a little loud so I suspended just above bottom of container and now it's quiet.doing great so far.

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