It has happened twice before for me when despite having a generator and a battery backup things did not go well. Its one thing to say I'll use a gas generator but I've come to realize things are not as easy.
This is also what I do although my power inverter is much smaller at 1000. Still the one time our power was off in the winter for a week, we hooked it up to the car battery in the driveway and ran the return pump, the fridge and computer. At the end of the week when the power came back on, everything was fine. We have a fireplace not far from the display so I did not need to have the heaters.
3000 power inverter (from harbor freight) hooked / clamped to my cars battery
Car in driveway, battery cables long enough to put inverter just inside my closed garage.
Two 100ft electrical cords running to my tank to run heaters and powerheads.
No need for lighting, skimmer, accessories other than flow and heat.
I'd probably hook up an airstone directly in the tank for O2.
Run the car LOCKED outside in the driveway feeding the power inverter on the garage floor.
Checking the car and inverter every 30mins via security cameras and in-person checks.
Start drinking coffee and calling the Power Company for updates, lol. since not much sleep happening keeping eye on car and inverter and tank.
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The power inverter is much more affordable and doesn't take up much space either. What I really liked was there is no maintenance on it (like starting up a gasoline generator a couple Xs a year to keep it in good running shape. I knew we would forget to do that.). It's a good solution for very infrequent outages.
I have a honda EU2200i around as well. Starts on first pull - super quiet, easy to carry, etc.
Academy
The lions share of the heat loss in a system like this is through the tank walls (conduction). Evaporation and radiation from the tanks surface do play a role, but if air movement can be slowed - the effect is minimal compared to the conduction through the walls. The airstones certainly don't help, but are a must have. Warming the air if possible would help.
Well, this summer, I had a whole home generator installed, so hopefully that takes care of it!
UPS systems can be extremely picky about the cleanliness of the power they receive by design. They are trying to protect your devices from receiving poor quality power that can cause issues for sensitive devices that are being protected by the UPS. My best guess is that the power being generated by the generator wasn't as clean as you think it was. Likely the type of sine wave being generated has high THD (total harmonic distortion) which the UPS is correctly detecting as bad power and is refusing to accept it. That seems to be a common issue with a lot of generators. Most likely you'll have to bypass the UPS like you did anytime in the future if you need to run off of the generator again.
What should you not run on generator? How do power companies clean it? Curiosity
Inverters
