Just following up on this thread. I finished my back up battery setup last weekend and for the most part it works pretty well.
Rather than use the included 24V power bricks, I'm using two MW 24V/10A power supplies that are installed in the top of the dry side of my stand. Each of these power supplies powers a 24 volt bus that I use to my two WE controllers and associated collective.
The battery is a 16S 200AH battery that runs around 53 volts when fully charged. If either power supply drops off, a relay associated with that power supply deenergizes and powers up a 24V/10A buck converter (installed on the opposite side of the circuit breakers pictured). When the buck converter powers up, it energizes a separate relay that transfers the loads on the 24v bus, including the WE, to the buck converter power.


I also installed a 1500W inverter and relay to power up my backup heater through a transfer relay (to the left of the Ink Bird controllers). The inverter is turned on by a drive port on one of my controllers and an associated power relay, when the water temp drops too low.
I ran this setup through a 24 hour test cycle over the weekend and it only consumed about 25% of the battery, keeping all return pumps, the skimmer, and 4 flow pumps running at normal speeds. However, I kept lights and UV on during this test so water temperature did not drop as much as it would in a real loss of power situation.
I am having a problem with the WE because they don't recovery cleanly in a power sharing collective but I'm going to open a separate thread to work through that.