Need a new ATO

[Rob A]

No matter which one you choose make sure your ATO reservoir is never filled with more water than your system can hold without overflowing if something gets stuck. I only keep a day or two worth of water in mine that way if the pump gets stuck on the only thing could happen is the 10 dollar pump will burn up. I have heard too many desalination stories from stuck ATO pumps pumping 50 gallons into 100 gallon systems. I use the cheap 50 buck Amazon float system and keep 10-15 gallons in the reservoir

 

[DoriReef]

No matter which one you choose make sure your ATO reservoir is never filled with more water than your system can hold without overflowing if something gets stuck. I only keep a day or two worth of water in mine that way if the pump gets stuck on the only thing could happen is the 10 dollar pump will burn up. I have heard too many desalination stories from stuck ATO pumps pumping 50 gallons into 100 gallon systems. I use the cheap 50 buck Amazon float system and keep 10-15 gallons in the reservoir

Yea will probably just do this, problem is I have a 25 gallon so will need a very small reservoir to not overfill, but see how it goes

 

[rtparty]

Upgrades? Like what?

I know on the regular one they changed the material the sensor is made from. I believe the Nano received the same update. The pump has a strainer as well.

I’ve been running the original Osmolator 3 Nano on my 25g tank for over 2 years with zero issues.

 

[Grog]

No matter which one you choose make sure your ATO reservoir is never filled with more water than your system can hold without overflowing if something gets stuck.

The voice of experience.

 

[Acro Junky]

ATO is a core piece of equipment and in my eyes part of the heart of your reef tank. Tunze #1 no other choices matter

 

[NatureDimensions Verified Sponsor]

Hi @DoriReef, just to clarify how the N-Fill protection works and why.

• After about 90 seconds of continuous filling, the pump stops and the alarm activates. Automatic refilling then stays paused for 24 hours.
• After 24 hours, the controller automatically resets and returns to normal sensor-controlled operation. It will refill if the sensors detect low water.
• Why it automatically recovers. If you’re away for several days and the ATO stays off, evaporation could leave too little water in the return chamber—potentially within two or three days, depending on your setup. In a worst-case scenario, the return pump can no longer maintain circulation, affecting filtration, heating, and skimming. That prolonged loss of circulation can be far worse than a slight, temporary overfill. The 24-hour recovery is designed to help avoid that situation.

Feel free to send us a message if you have any more questions or thoughts. We love discussions like this—real-world experiences, ideas, and feedback help us make our products better.

 

[DoriReef]

ATO is a core piece of equipment and in my eyes part of the heart of your reef tank. Tunze #1 no other choices matter

Yes just bought one

 

[Webbed Feet]

Years ago I purchased two USED Tunze ATO systems. One of the cheapest ones with float only, and one of the more expensive ones with float and optical sensor. The float only went on my 25 IM AIO and the better one my much larger display tank. The USED systems have worked flawlessly other than I had one used Tunze $28 ($35 now) pump fail and need replacement. I'll blow your mind, it blew mine when it worked. The Tunze ATO to the display tank pumps from my garage 50 gallon fresh water reservoir via 1/4 tubing, up 12 feet, across the garage ceiling, back down to a crawl space, back up about four or five feet, for a total of a 90 foot run, and it works!! The little blue and grey $35 pump ran it at first, then I replaced it with a $85 Turbelle High Jet pump just to calm my nerves about overworking the cheap pump. That was a couple years ago. It has all ran perfectly. The Tunze wiring design (not hard wired) allowed me to add 90 feet of wire from pump to control unit that almost no other system was designed for.

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[1ocean]

Had Red sea on my last tank,,,had to replace the sensor twice...
New tank is getting the Kraken and Hydros system so I am trying Hydros ATO this time.

 

[Uncle99]

There are a ton of ATOs which work great.

The important part is to use one with two sensors, and also, plug it into a Multi Timer which allows power for only 1 minute every hour.

Now, if sensor 1 fails, sensor two stops it, if both were to fail, then the multi timer only allows 1 minute if water each hour which is almost exactly, a normal evaporation fill in an hour in my system.

Example shown below, there are a few manufacturers