I agree with the other poster that said to give it more time. People tend to underestimate how much flow their coral (and their fish) can take. Many of us are running more powerful wavemakers in the same tank with success (I'm running a Nero 3 that peaks at nearly 1200 gph during the pulse schedule periods during the day).
To answer your questions:
- I'd give it a week or so to see if things get better before buying/installing anything else. Less is more many times in this hobby.
- If some/all of the coral don't improve, consider powerhead and coral placement. Even with a powerhead at 800+ gph in this tank, you can use powerhead placement and your rockwork to create zones with different flow levels. For example, place the powerhead in the upper/middle part of the tank and point it at the opposite wall. This keeps it from creating a sandstorm and, combined with your strategic rockwork placement, should provide some respite for your bottom-dwelling coral that prefer low-flow (like the acans). My Nero is pointed right at my sticks (birdsnest, digitata, and stellata). But I have frogspawn and duncan thriving on the other side of the tank where my rockwork and the deflection of direct powerhead flow makes for a low/moderate flow zone. Even with the powerhead is cranking at 1200gph. I also have zoas and mushrooms doing fine in high flow.
- One or both of the above should fix the problem. If it doesn't and you're not planning on growing coral that demands high flow, then downgrading certainly won't hurt. But again, I don't think you'll need to.
