Yeah, patience. I cycled my 30 gal for almost two months. Actually it was cause I missed the ammonia spike somehow (I tested every few days and seriously missed it), and caught the very end of the nitrite spike (also no clue) and by the time I figured out to do a nitrate test, it was almost two months later.
Besides, you're not doing fishless, are you? I know you siad you already have fish in the 20 gal in another post. Fish-in cycles take even longer than fishless, because its a matter of getting the system gradually used to the ammonia etc. Don't replace filter cartriges, and don't overclean them unless they are so dirty that they're not doing their job cleaning. The extra gunk in the filter would prolly only help the bacteria establish.