Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Nitrifying bacteria do not need to be under water, but do need to be damp.
They need high oxygen, and ammonia, and a few minerals.
Optimum conditions include pH in the 7s, GH and KH over 3 German degrees of hardness.
Keeping it cooler is just fine, it will slow the growth rate of the bacteria, so they do not need as much oxygen or ammonia. (Do not freeze).
Here are a few options:
No power method:
Put the media in a 5 gallon bucket with maybe a gallon of water with dechlor (used aquarium water is fine) and a few drops of ammonia. Swirl it around a few times a day, and add ammonia.
Keeping the actual filter going:
Set up a plastic storage bin, any size as long as the filter fits on it (I have used a 5 gallon bucket for a Fluval 404 or a Rena Filstar XP3, but square bins work better for HOB filters). Keep the bin full enough so the filter runs and add ammonia.
Keeping the media in water without the filter:
Set up a plastic storage bin or bucket filled with enough water to cover the media and run a bubbler or small fountain pump on it. Feed ammonia.