How does this ATO work?

[questionablereefing]

How does this type of ATO work? I don't want to do float switches, they seem to have mixed reviews. If not what is a reliable, cheap, and safe option for my nano 5g? 

[jahnje]

That's just a relay. It will run a small electrical current from one wire to another.  When there is no current the relay is closed, and whatever is plugged in will be on, like a pump. When the end is submerged the relay will be open, and no power will run through the cord.  The reason these are generally not used is four fold. People don't like the idea of current running through the tank, as i can mess with fishes electro chemical signals.  Can ground out against some other thing in the tank and electrocute your fish.   Metal is in the water and can poison your fish with aluminum or copper depending.  In a reef tank this will corrode in a bloody hurry, and I'd be really surprised if you got more than a year out of it. 

 

Or it's just some other kind of float, and will have the same problems as all of the others. 

[Boggers]

That is a float switch not a relay. (I think based on the design) similar to what Jahnje wrote but line turns off/on when water is floating the white bobber or letting it hang and turn the power on.

 

The Smart Micro ATO is the smallest I have seen but the price is not as nice. After that I would look at a hamster water bottle ATO. 

 

[questionablereefing]

I've tried the hamster water bottle, but with no success  

If not, how does the Tunze Osmolater Nano sound? 

[Boggers]

Very reliable float switch

[NanoRox]

I just installed a Hydrofill ATO TI  yesterday and it uses a relay (uses graphite leads).  Had good reviews so will see how long it lasts. 

[Dougefresh35]

ATO micro is far and away the best ato I have ever used and is super small?