. How long should the tank be cycled without fish? Assuming filter/rock material from an established tank.
When your nitrite has subsided to near zero value, and your nitrate levels begins to noticably elevate (usually pretty linearly). This can take an indefinate period of time. Remember (charge values ommitted):
NH4 (ammonia) -> NO2 (nitrite) -> NO3 (nitrate)
Ammonia will be the first by-product of organic consumptions, then nitrite, then nitrate. Specific bacterial species are responsible for each oxidization process. What cycling essentially is is giving each bacteria species the chance to populate sufficiently to cope with the specific nitrogen compound it utilizes for metabolism. Ammonia oxidizing bacteria will be the first to populate, and when it does, ammonia will drop to near zero. Then nitrite oxidizing bacteria popultions will grow to utilize this newly available nitrogen source (NO2). When populations reach critical mass, nearly all nitrite available will be utilized by these bacteria, dropping the nitrite levels to near zero, and consequently increasing nitrate levels (NO3). At this point, your cycling process is "complete." Note: the nitrogen cycle is a cycle, and can never be really "completed" in the true sense of the word. Denitrification is a whole other story.
Buy a test kit. This is the only way you can tell when your tank is ready to inhabitation by fishes and corals.
2. Just how does one know if s/he is buying recently harvested live sand?
I'd buy from a reputable dealer, like Marine Depot, Harbor Aquatics, or Jeff's Exotic Fish (there are plenty more). To be honest, there aren't a whole lot of visiable indications to gauge the quality of live sand when you first receive it. In a few weeks, you should notice a diverse specification of infauna in your substrate if it's quality live sand. Of course, by this time, it's already too late if you've bought poor live sand. Again, best recourse is to buy from reputable dealers. Ask around.
3. What is the proper procedure for introducing live sand into a FO tank? After cycling, or before?
Before. If you introduce live sand post cycling, you'll go through another bout of nitorgen cycling. Any time you expect die-off, you can expect "cycling" (population of bacteria finding equalibrium with particular nitrogen compounds) to occur.
[ September 25, 2001: Message edited by: Leonard ]
