I have a kill-A-watt gizmo too, I should run it on my setup, although since the switch to LEDs, I've been a whole lot less worried about amps.
When going on vacation, I split heaters, pumps and backup batteries onto 2 circuits, but otherwise run the whole thing on a shared 15A breaker. 15A is a lot of juice. I use big UPS backups to ease the startup surge after a power outage. I think most issues would come from a full power startup of a whole tank. In fact, even the apex helps a bit, as it powers on things in timed stages after an outage.
**** Anyone doing their own wiring should be aware that while it is technically legal to run your own wiring, it is not legal to hook it up. Get an inspection done on any wiring you do. Insurance investigators are REALLY good at finding home wiring jobs after fires, and good luck getting your money out of them if they find something. Be safe and contact a professional, don't ask us idiots on the internet! ****