My experience with caelpra is that is goes sexual when it is really dense and fighting for space. Try keeping it pruned so that light penetrates through the bunch. You may also consider changing over to chaeto. It is a different type of macro algae that work very well is refugiums. It does not go sexual. Typecially there is several members on the board that are willing to send some for the cost of shipping, in fact I could probably send you some if your on the West Coast.