Prepping for new tank

[e46er]

i have a couple evergrow 48" controllable LED lights best colors ive ever had.
I LOVE my apex and wouldnt set up another tank without one
I run 2 little fish reactors with rowaphos all the time and intermittently run carbon in the 2nd

I run an ATO with a 50 ml/min peristaltic pump on a timer from the apex takes a while to figure out your top off but I put very little faith in $6 float switches.
I have a 15G top off container and my sump has 15G of room so even it was full and the apex failed and stuck on I wouldnt overflow unless my return failed at the same time and I didnt notice.