I use tap water for the sponges and tank water for any other part of the filter media. The sponges get too dirty to clean out well enough in tank water, esp on my bigger cannister filters. I don't worry about any recycling as my substrates hold bacteria as well. If you have no established substrates and ornaments, you would have to worry about a mini cycle. If the tap water has been treated with a dechlorinator overnight then you won't have to worry about the chlorimines or chlorine.