No fish ..keeping tank cycled

[RedFish]

I've just moved an elderly female betta to a tank that I can keep shallow for her, she is loosing her strength and finds it hard to get to the surface of her 5 gallon.

I want to put another betta into the 5 gallon and want to keep it cycled while it will be empty for a few days until I get the new betta.
Could I move another betta back and forth daily from his tank to the empty one to keep both cycled?   As I write this, I realized that may well be too stressful for him.

If I leave the empty tank as is, and put the filter into another tank to keep it cycled, and then do a major water change on the tank when I get the betta?   Would that be a better plan?

This assumes that I can find a gorgeous betta early next week!

[BigDaddy]

If it is only for a day or two, you really don't have to do anything.  The bacterial colony may die off a bit, but you should be fine otherwise.

For more extended absenses, you can either add a couple of drops of ammonia to the tank daily, or you could leave some fish food in the tank to slowly decay.  Either option will keep the filter cycled.  Just make sure to do a big water change before you introduce your new inhabitant.

[RedFish]

Once again, thank you BD, your help is appreciated !

I'll be scouring the stores for the next few days....