ATO failure

[gregzz4]

I hate wet floors!
Although I mostly trust my Tunze 3155, I have it plugged into my controller and a float switch in the return section. This will only allow 2 gallons to flow IF the ATO controller sticks 'on'.
The ATO has access to a max of 9g, which in my 115g system would drop my DT from 1.026 to only 1.024. And my sump could handle it all; unless the return pump were to then stop!!