Few days ago, my IM Hydrofill TI ATO controller failed. Luckly I noticed this before any water spilled onto the floor from my IM 20g tank. Also the change in salinity wasn't too wild to cause harm to any livestock. However this has made me restless and I want to add a backup switch to prevent this in future. I came across this float switch http://a.co/d/bUdg4rr. However it might be too big to fit in the tiny sump from my AIO. Looking for better alternatives or other suggestions for this. I basically want something that will fit in the back chamber of a AIO tank. Since my ATO was still in warranty, I am getting a replacement for the probes, but again it might fail again. I want to give this ATO controller another try before moving to expensive ATO alternatives.