I have not decided to turn off the flow. It's got sps in there that needs the flow. I do however only have a Refugium as filtration and my flow is setup to try to keep food and what not, in the display, instead of going over the overflow. So I think I just accidentally set it up so they can spawn easily in this specific tank.Congradulations!
If it's any consoltation, the Stienhart Aquarium's breeding progrram with Acropora millipora has results from only about half the colonies.
Frontiers | Kinship and genetic variation in aquarium-spawned Acropora hyacinthus corals
Recent scientific advances in ex situ system design and operation make it possible to complete gametogenic cycles of broadcast spawning corals. Breeding cora...www.frontiersin.org
Have you thought about turning off all the water pumps when they spawn for a couple days and just use air bubbles for circulation?
Thanks for the link though, I love stuff like that