I think using a siphon break in par for the course on most ATO set ups. Also you can adjust the temperature reading to match your correct one. Reef Beat- Home- Temp button to next screen, Hit center temperature button > next screen scroll down to temperature adjustment.So I could not figure out why the return chamber kept getting overfilled. My plumbing is spot on, then I realized what was happening. My red sea is back siphoning because the ato storage is higher than the sump level. So I have to use their stupid siphon block which is so gigantic and stupid it doesn't work with my trigger ato reservoir. It has to be in the dang reservoir so my five gallons is barely four now. This unit at the time seemed like a slam dunk buy. But all the little extras are poorly thought out, its insanely loud, inaccurate ato monitoring, the temp is never right. So all these extras I thought made it worth the price don't really work. The temp gauge is so high in the sump it's always five to ten degrees off what the controller and glass say.
So anyway. I guess that's "fixed" now.