Wow...that's an issue I never really paid that much attention to. I guess I make mine a week after the culture blooms. Once the culture takes off I wait a couple of days until it looks real good then start to feed from it. Then a few days later I make my new cultures. At that time the culture is going really well. Hydei does not reproduce as fast as the Melanogaster so if I were you I would always keep a culture or two of the Melanogaster around as a backup. Of course depending on how many frogs you are feeding. Just be careful to ensure a culture crash doesn't cripple you.