Quarantine/Hospital Tanks, Filled Or Empty?

[Piperspop]

Hi There,
I was looking through old threads regarding quarantine/hospital tanks. I have a couple empty tanks, one 10 gal, and one 29 gal. I have extra filters running on each of my main tanks anyway, so I could be up and running if needed. My question is, do you always have quarantine tanks filled, or can they be left empty until needed? What do you do? I am posting this in Marine, as for me its WAAAY more expensive. Thanks for any feedback.

 

[Amphiprion]

I keep seeded media handy and set it up as needed. I simply use water from the main display, as well. That way, there is added stability to the new setup and you get similar conditions as the main tank. As an additional bonus, the display gets extra water changes as a result.

 

[almo75]

I used to keep one set up all the time. It was just a 10g and my wife needed it for feeder crickets for the lizards. I usually have a garbage can of water ready and waiting for water changes. This weekend, when running errands, I will pick up another 10g. I'll just pull water out of the can if needed as opposed to keeping it set up.
After a bout with Ick in the main tank and sitting fallow I will always have something on hand. I do not want to go through that again.