I setup a quarantine tank today and was wondering how do you keep the bacteria alive in the tank if you leave it running with no fish in it. I set it up for my tang but cant catch him so now there's no fish in there.
I have tropical not SW but the teory is the same. I feed my QT a NLS wafer every other day and do PWC once a week. The small amount of food wasting away all week feeds the nitrAtes what they need to keep going.
I don't know what you feed your SW fish but some type of flake, pellet, or wafer fish food would work the same way.
My nitrAtes don't go above 5ppm but it's enough to keep the tank cycled while it's empty.
You never want to put your QT filter on your main tank. If there is anything contagious from the fish in your QT it could be passed to your main tank. It's why we isolate fish.
Also if you don't want to keep your QT up and running all the time, you can keep the filter running on a 5g bucket. Just do everything the same as you would if it were a tank except you can let the nitrAtes get much higher and not worry about the health of your fish. That way it can cycle your tank within days of setting it back up, because the filter is already full of nitrAtes.
I hope this can help you, I know SW and Tropicals are different but how different I'm not sure. So everything I said is to be done with the statement,
"ADJUST FOR SALTWATER FISH"