Nano ATO failure

[supermarvin76]

I bought my Tunze Nano ATO new this past spring and once last night and again about 5 minutes ago it activated, but did not shut off. I don't know if it would have eventually turned off, but each time I unplugged it.

I am lost, and really not in the mood for manual top offs.

Advice anyone?

Thanks.

 

[rvitko]

It does have a safety time out that should shut it off even if the float failed. Be default this is set to 1.8 minutes and it can be extended to 3 minutes.

Causes of this I have seen, are as follows-

1) Critters, especially sea urchins and cucumbers can insert their legs in and move the float. Small stomatid snails can do this as well, especially if this only happens at night, this would be a prime culprit.

2) The magnet holder or a magnet holder cleaner near by. If the glass is less than 1/4" thick this is a possibility as the magnet or a nearby magnet can pin down the float switch which is a magnetic switch. The black ring is a magnet and it flips a switch in the post. If the float is at an angle and not straight up and down, it is likely attracted to a magnet.

3) Something near the controller is creating a magnetic field and causing interference. A ballast or wireless control device or LED driver are prime culprits and along with their associated wiring should be kept at least 18" away.

4) Something is wrong with the controller.

 

[lilphil26]

My 6 week old Tunze nano just did this to me tonight. I took the switch out and it seems fine. Luckily the timer shut off the pump before a major disaster. There were no snails or foreign objects in the switch. I am hoping it was just a one time issue as my 25 gallon tank goes from 1.025 to 1.023 when it pumps until the timer shuts it off.

 

[lilphil26]

The only thing I can think of is that is the float switch wasn't perfectly vertical. It worked fine for several weeks though however.

 

[rvitko]

That could cause it, be careful that the magnets are lined up correctly or they will rotate so the poles line up and this can affect the float switch. On thinner glass it can make it easier if you use a shim of 1/16-1/8" rubber or acrylic between the outside glass and the magnet.