This is the only stuff I've found that actually works:http://www.drtimsaquatics.com/freshw...m-products#one
Make sure to have careful read about cyling guide:http://www.bettafish.com/showthread.php?t=47838
You need a drops test kit for ammonia, nitrite and nitrate
Soaking a sponge or using a few gallons from an established tank isn't going to produce a fully cycled new tank, but it could help. However, if you took fully established media from one source to another (like an extra sponge that's been running a month) that would help a great deal.. still wouldn't be INSTANT cycle. Just help it.