Gyre help

[USMA36]

I am running the above pump on a 90 gallon 4' long tank. The pump is on the right side placed horizontally about 1" below the surface. I am having problems determining the right flow and settings. I have been running 75% gyre during the day and 25% pulse at night. I keep getting giant sand dunes. What would be my best options for adequate flow without the sand dunes. My torch coral seems to like the gyre mode best. On 50% pulse with torch in middle/middle of tank seems to get too much flow. Any help would be appreciated.

 

[USMA36]

I am trying 50% pulse .4 seconds. Less sand moving but torch doesn't seem as happy as gyre mode. It's a much more violent back and forth opposed to the gyre having a more gentle waving. Determining proper flow has been one of the more difficult learning curves to overcome.