I mean, like anything your tank cannot support an infinite # of pods - eventually there will not be enough food to go around and the population will die off. I'm not sure if pods are the type of population where just the excess will perish, leaving behind a still large population, or like hermits and snails often are - if you over stock, they usually almost all die from slow starvation around the same time.
As far as a quantity of "how many is too many" - not a clue!
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