My rock work is in the middle and centered, so to speak. I keep a powerhead in the lower back right corner, which runs 24/7. This creates a constant swirl on the bottom along the sand bed.
I then have another 2 powerheads up higher. They are on opposite ends on a wave maker, set for a full minute that alternate. Then I have my returns hitting the glass into the corners, that creates a downstream. Sofar my small SPS GARF Bonsai is happy, and the rest of my LPS are not affected. So far so good. Hope this helps.