ATO issue.... maybe
 

OK so the JBJ ATO is set up.

But once the pump is shut off.... water continues to siphon from the res to the sump.

I did as directed and the end is not submerged in the sump.

Not sure what the issue or correction might be.

If anyone can help out, that would be appreciated.

Thanks.

Is the water level in your ato reservoir higher than the level in the sump?

Did you use a check valve? Or is the reservoir placed higher than the sump? If so, gravity is creating the siphon, in which case a check valve would work.

The ATO pump can not be higher them your sump. It has to be even with bottom of sump or lower, it's a matter of gravity.

peristaltic pump will stop this but I'm not sure of flow rates

It is at the same level.

It is bottom of res... hose goes up... angles down into sump.

Does the angle of the hose have any bearing on it?

The res is tall.

angles down into the sump.

It is called gravity and the pump is starting a siphon. The reservoir needs to be lower than the output, or use a check valve, or use a different plumbing method.
I thought that you were putting your reservoir in the basement?

The output end of the hose into the sump has to be the high point, there can't be a downward flow.

You have to make sure the output of the top-off hose is higher than the water level you run in the reservoir or you're going to get gravity feed.

EDIT:

^^ what he said...