John wrote:
....

Thanks for any help. I'm also going to be dealing with a backup unit
(one of the battery ones most likely) next spring to make sure I'm
covered when spring hits, since it's not unheard of to lose power
around here (southeast wisconsin).

I have two comments.

First I suggest you consider a water powered pump rather than battery
for backup. Battery power will not last all that long and batteries get old
so a few years down the road you may only get a few minutes of protection
from the battery powered backup.

Second, while reading your message, something kept whispering in my ear
"Check the foot valve" or what ever kind of back flow valve(s) you have. It
just sounded a little too much like you are getting a leakage coming back
into the sump from the water you just pumped out. Nothing certain, just a
feeling I have about it.

--
Joseph Meehan

Dia duit