Customer Reviews
  1. Does not work consistently.
    Performance
    20%
    The first one I bought 4 years ago is the only one that ever worked. I have bought 4 of these. I wonder if they changed manufacturers or quality of parts. The sensor will work for the first time the water level is low. Once it stops, the sensor will not pick up the low water level again until you unplug the system from the electric sort and plug it in again. The pump will constantly turn on and off even when it is not pumping.

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  2. Major issues
    Performance
    20%
    I currently have 2 of these. Only one is in working condition. One's on a biocube 29 and One's on a 30 standard. Both units have failed. I had a pump burn out on one unit. Bought a replacement pump. On the other unit the float sensor just wont work. I can hear the pump power up when i plug it in but it wont pump water. I have purchased 3 of the oz minis over 4 years. The last failure was the small circuit board where you plug in power got so hot it melted the plastic housing. You could smell electrical burn in the whole house. Of course it was in the 26th month of ownership. I will never buy another product by Tunze.

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  3. Good unit if you only need it for a year :)
    Performance
    40%
    I did not have the plug unplug issue but I do think the default fail safe it comes programmed with is pretty dang conservative so I'm not surprised people have that issue. I have had this unit for about 2 years and it worked great for a year and a half then the pump stopped working one day and that was that. I'm sure it's under warranty but their warranty process is a pain plus I should bite the bullet and upgrade to a better system.

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  4. Same problem...
    Performance
    20%
    The sensor will shut off the pump but will not turn the pump on. I have to cycle power for the pump to work.

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  5. 1 is a yay the other a nay
    Performance
    20%
    Bought 2 of these, 1 works as intended, the other requires the same unplug then plug it back in to work every time defect after a week.

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  6. Works great
    Performance
    100%
    Great product. Works as described. No problems. Reliable so far.

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  7. I have three for all three of my tanks and love them!
    Performance
    100%
    I love these! I use one on each of my tanks and I have three tanks total. I haven't had any problems with them. When installed correctly they work perfectly. Read the instructions and follow them. It's got a build in fail safe system that gives you a peace of mind.

    I see some bad reviews on here of people saying they have to unplug and replug in the power cord to get the ATO to work. This is a failsafe built into the device. If the pump runs longer than a couple minutes it has to be reset. If the float value gets stuck it won't keep pumping and pumping and either flood the inside of your stand and totally throw off your salinity. Something must be causing you float value to become stuck. I have three of these and that’s not a common problem.

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  8. Didn't last.
    Performance
    40%
    Worked perfect for a year and a half. Then one day I noticed it wasn't topping off. Unplugging and resetting worked for a few days then it quit working completely. My 3155 is still going strong and is much older.

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  9. The first month it worked great......then it started having the same problems of several others that have posted. I unplug it and then plug it back in and it turns on......works for 2-3 days and starts the same process all over again. A $100.00 waste.
    Performance
    20%
    Again........first month it worked great.......then it stopped working. Had to continually unplug and re-plug to get it to come on... Quite a few others have had the same problem.......$100.00 wasted and to help from anyone. What a messed up system.

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  10. The standard for smaller tanks
    Performance
    100%
    Tunze quality on a smaller package. These are bullet proof top off units. Those who have problems are not reading the instructions and have it installed in an incorrect area. You get a two year warranty on this brand. Who else does that? Nobody.

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