When should ATO start pumping?

[Fritz05]

I bought a cheap ATO from Amazon. It does not seem to start pumping fresh water until the water level has decreased by 0.5 cm (one fifth of an inch). Is that normal for an ATO?

 

[MichaelReefer]

It just depends on the unit I assume. I dont think there is a set "drop" amount for all ATOs.

 

[iaa12]

I bought a cheap ATO from Amazon. It does not seem to start pumping fresh water until the water level has decreased by 0.5 cm (one fifth of an inch). Is that normal for an ATO?

There's generally a lower and upper water sensor of some sort. When the water goes below the lower sensor, it starts pumping until the water reaches the upper sensor again. And then that repeats. The distance between the two sensors is going to determine how much the water level will drop, and it's different on each ATO.

 

[Rmckoy]

You could adjust the float or sensor up to come on that much sooner ?

 

[iaa12]

You could adjust the float or sensor up to come on that much sooner ?

That's not possible with every ATO. My Hydor ATO has all 3 level sensors built into the same assembly, so while you can move the whole sensor assembly up and down, the distance between sensors cannot be changed.