Power cuts are rare but they still do happen in this day and age. Let's say the heater or chiller went off. If one was to occur, what's the best way to protect the fish & cause the least amount of destruction? Thank you for your advice.
I recommend to always have some type of backup power supply, mostly those UPS type of units so at worst you can run a heater or chiller for a long period and maybe flick the filter on and off to prevent the beneficial bacteria from dying off (maybe even a small battery operated air pump to mix the water surface to get a good gas exchange going as well).