Water level in ALL my tanks never changes one little bit??
The purpose of a proper running overflow means levels only change in sump????
OP has a sump(pretty nice)....
Is last chamber in sump an ATO?
Ditch it or the last overflow if it is not IMO
The added space to last space with return pump will allow longer time between top offs.
More volume in last return section is always tops on my list in my sumps.