I have programmable Vortec on random reef-crest and then night mode at night. At night the flow cut way back and during the day the flow is really variable from really high to very low, randomly. The healthiest Gigantea I have is one that is very high flow and high light area.
I really like my Vortech. I think the reef-crest mode is really great for SPS and Gigantea. It really simulate the flow that they needed.
My controller control both light and the Vortech, as the light turn down for the night, so is the water movement