never a flood, ive come close twice though. i forgot to turn my skimmer on full flow after the break in period, and i caught it late at night half a inch from overflowing.
second time was late at night i figured why not fill my sump to the top, the power hasnt gone out in over 10 years. jinxed myself, next morning the fluval FX5 on my 90g freshwater shorted and killed the power in my house. luckily i was tired the night before and kept my sump at 1/3 full. with the power out, my overflow caught enough water to fill my sump 2" from the top. if i filled it the night before, i would have had a flood