cich1 said:
i would recommend that you cycle any new rock your going to add in a seperate bucket with a ph and heater before adding it to your tank,
i bought a 4.5# piece to add to my nano and was told by the lfs that it was fully cured but i decided to put it a bucket anyway and 2 days later ammonia was off the scale, it took nearly 3 weeks for that "fully cured" piece to zero out
I think that cich1 has a good point. Really you should set up all your rock in the beginning and let your tank cycle. As far as a store is concerned rock may be fully cycled, but they're not thinking from the standpoint of a nano tank. Even transporting a piece of rock from the LFS to your house, you're going to get a small amount of die-off. This is normally somewhat minimal, and not too much concern when you're talking about putting it in a 55g tank, but it can have a huge impact when you're talking about a 5g tank.
There are things that I'd do with a larger and inherently more stable system than I'd try with a nano. For instance, I wouldn't try to re-use a sandbed in a nano. I'd take a small amount of the old sand and use it to seed the new sandbed, but I'd use all new fresh sand to avoid the die-off that's just part of transferring any sandbed. If I felt the need to add more rock to an existing nano, I'd only add small (think less than 1/10 total volume), pieces over a long period of time, or I'd put them in a 5g bucket with a PH for a week, and do a couple water changes during that time before adding a bunch at once.
B