I had originally started a 10 gal as a Q tank for a banded eel that I bought about a month ago. I ued about 10 lbs of lr and some of the crushed coral from my 150 gal display tank. No spikes in any readings and the eel is doing great. I just don't understand why there is such a debate over the idea of using aged rock and sand in a different tank. The rock already has denitrifying bacteria and the substrate has already aged. Why would anything spike if the proportion of species to lr/ls is the same? The obvious answer is that it wouldn't and you could in fact start a sw tank overnight (if you had enough lr/ls available). Agree?