Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
It is MUCH better to have water flowing through it. The bio media has a lot of very small spaces, and without water movement these spaces will not have the high oxygen and ammonia flow that the bacteria need. The outside of the media will grow some bacteria, but it won't be much.
Can you hang them from the side of the tank near a filter or bubbler? Anything that moves the water will help.
Do you have an extra air pump or power head? Use either of these to draw water through the new bio media.
Set up a small "tank" (as little as a gallon pickle jar or whatever!) Put a bubbler in it and all the media you want. Then feed it with ammonia per the fishless cycle.