We live in the coastal 'lightning belt' and possible power disruptions during sessions was a real problem this summer. I have generators available but do not have -nor want- an automatic transfer switch. What we DID want was the ability to do an emergency rinseback with power. I checked with support and they recommended a minimum of 1200va battery backup. I found a namebrand 1500va model on Amazon that did NOT require software/computer monitoring but simply shows "time remaining" while in use.
https://www.amazon.com/gp/product/B06VY6FXMMIf you kill the heat on the pureflow, which is very quick & easy to do during session, it gives you approximately 30 minutes of runtime for the system. (With heat on, the time available drops to 9 minutes.)
System power requirements (@ 123v incoming):
Pureflow heat off: 82 VA
Pureflow heat on: 442 VA
Cycler: 108 VA
Related - Network for Lightning and Thunderstorms in Real Time
http://en.blitzortung.org/live_lightning_maps.php?map=30