I have three ATO's, and my fav most worry free SILENT is the avast I have on my 60g. It's been set up for a full year, and hasn't failed me yet. Which reminds me, I need to clean it one of these days..... :blink:
I also hava a tunze nano and a tunze 3155 (on a 75g planted), which have been set up for 6 months now. The nano failed when a snail blocked the sensor, didn't overflow, instead it just stopped adding water.
If you have a sump, go with a Avast ATO, you won't be sorry.