I have what would be considered high flow for a zoanthid tank. 300gph Aquaclear and a 100 GPH powerhead on a ten gallon tank. That's 40X turnover. However virtually all the flow bounces off the front glass which disperses the flow.
I also have Zoas in very low flow with marginal lighting and they look great. The flow is maybe 200 gph spread over 10 inches of weir and the zoas have covered the back and left wall.
I suspect part of the flow requirement depends on where the colony originated.