Not clicking with me, seaham. I mimick a power outage every week when I do water changes......
When I siphon water out into the sink (like when the power dies and water is siphoned into the sump - assume sump has room to hold excess, which it should)....the
HOB-OF box stops siphoning, correct?
Ok...sump is almost overflowing and
HOB-OF box has stopped flowing because water level dropped - we're here now and it's just like my water change (assume the sump is full)
I habd fill my tank from water jugs which is exactly like.....Power comes back on
......pump returns from sump into main tank, right?.....Ok, tank water reaches "teeth" on
HOB-OF box and bada-bing
Siphon restarts and all is back on track because.....
The siphon itself (U-tube) never took air. It's always primed and ready for the water level to return. I do it once a week. Try it.
The folks you're speaking to may have set up such that that siphon actually "breaks" and takes air. Then yes, it will flood. if set up correctly, it doesn't do that. hope that makes sense.