I'm a small tank for sps---a 54 wedge. I run my tank via a 30g sump in the basement with an Iwaki 100, which is way overkill, but it's what I ended up with: since they allegedly last forever, I figure I'll have to throttle back for a long time.
The flow comes out divided between two sea swirls aimed at each other, but slightly down, and it's enough just not quite to make the sand walk, but I do have to brace things so the sand doesn't creep out from under them. Because the two Sea Swirls are not coordinated, they both provide chaotic flow in the mathematical sense and keep my rocks swept out and my fish exercised. Nothing gets hit directly, and I have yet to know how well this does with sps, because everything is suffering 'new tank syndrome' since the move. The lps are ecstatic. The sps are starting to show the tips of polyps. I would say to anyone contemplating a basement sump that half the pump I've got would probably do ok to get a good flow up a 15' rise.