Shock to the system?

[stratmaster]

Guys my tank has been sitting for at least three weeks running without any fish in it and a bunch of live rock. Since I lost all of my fish, the LFS recommend I let the system run for 21 days just in case the cause of death was ick. This way the ick would not have a host and will die off. Anyway the three weeks is up, I want to get some fish real soon and my question is.... when I throw a fish in there, is it going to be a shock to the system since it's been running for 21 days without any fish? Or no since it's been up and running for three years?
(By the way is this true what the marine biologist is telling me? Ick has a life of 21 days and will die naturally without any fish to host on to?)

Thanks,

Steve

 

[mdaniel2882]

First....21 days is not enough for ick. the life cycle is 4 to 6 weeks depending on the temp of the tank. after that you shoulld be fine if you add slowly.

any yes...the life cycle of the ick will end with out a fish to host

 

[InfernoST]

Have you been providing an ammonia source during the 21 days to keep your nitrifying bacteria alive? Leave the tank empty for another 2 tp 3 weeks. Are going to QT your fish or just acclimate them and throw them in your DT? If you just acclimate them and put them in you may wind up with the same problem that wiped out your tank. If you're going to run through QT you could get a couple of fish since they should stay in the QT for several weeks anyway.