Pods (in general) multiple fast, but their ability to reproduce in your tank will be limited by available food, shelter from predators and temperature. Predators aren't only your fish, other larger pods like amphipodds and the like will eat your smaller copepods. Your ability to culture Tisbe sp. pods will then be dependent on your ability to keep out significant populations of other pods etc... in closed systems you generally end up with only one type of pod after a certain amount of time, but start off pretty diverse as things are constantly being added to the system like new live rock and frags etc.... Well that is enough run on sentences for one post.
