8 hours of top off/flooding kills almost everything

[xenon]

Hard lesson.

We never use a top-off container larger than what would fit in the sump if our ATO fails.

[kien]

yikes! Sorry to hear man.. I lose sleep over this worry. To combat Murphy here I too use a smaller ATO reservoir (8g) as well as a secondary emergency shut-off float switch to kill the ATO pump in the event that the water gets too high in the sump.