once they hatch i would sat turn your filter off. do a water change every day to compensate for it.
Given the Biocube design that would kill all water movement in the tank as it only uses one pump for everything. You could probably get by this with a small koralia or similar on low speed so they don't get diced. I'm usually pretty hesitant against raising fry in a display tank just because of how much stuff eats them that you don't think about, but they're so small they become bitesize for lots of things.