Switching tanks mid cycle.

[G_matto]

So, I may be the most indecisive aquarium owner. About 2 weeks ago I set up a 20G long for a fishless cycle. In the time I've been waiting, I have found a 29G tank collecting dust in my parents basement and was wondering what the best method of switching tanks would be in order to maintain the beneficial bacteria in my filter. I only have access to town tap water but do have a bottle of Prime. Will there be any risk of killing the bacteria after I prime the water? Are there any other risks for the bacteria that I may be unaware of? Any advice is welcome.

Thanks so much,
~Greg

 

[G_matto]

Also, I'm running a fluval C3 power filter if that helps any. I was thinking of letting the water run through the filter without the biological filter tray in but I don't know if that's effective or even needed at all.