Doing super frequent water changes.. what can go wrong?

[Delphinus]

I honestly don't see how the bacterial cultures would be adversely affected (at least in a significant sense). The amount of free floating bacteria is minimal compared to the amount bound to the substrate and rock. I've known people to do 100% water changes (and done some myself) without there being a cycle afterwards. I'm thinking in Kevin's example, the 3 60% water changes in quick succession maybe somehow shocked the system and there was a bacterial dieoff as a result. I'm not sure what happened there though so I guess I shouldn't speculate. But theoretically, smaller water changes more often should really in fact impact the bacterial cultures even less than the typical weekly/monthly changes.

So I think you're good to go.