optimal flow rate
 

I'v been thinking about flow rates on my 77G tank. Right now I have 2 Seio 620's and 2 MJ 400's circulating the water. There is also a Fluval 405 which is only used for mechanical filtration and carbon. I guess that gives me 2040 GPH. Is this adequate for a tank this size? This is assuming that I will eventually want a few SPS in there.
I'm not happy about a few dead spots I can already see in my tank. There's nothing in there except for the LR and a Sea Hare. What I think would work really well is a powerhead that has an automatic 180 degree rotation back and forth. A couple of good sized units like this placed at either ends of the tank would be perfect I think.
Would a Hydor Koralia 3 do something like this?

no opinions on this subject?
Someone must have some advice......

Well, the answer is it depends. What kind of corals are you going to keep? Even if you have SPS, if there is a hammer or zoos or other "soft" corals, you don't want really high flow. If you're just going SPS, then load up. I had about 6,500GPH in my 75 with all SPS and bare bottom. Corals loved it, fish put up with it well. If I had a LPS or softie in there, they probably would have had tissue removed. So it depends....

I had a 110X flow rate in my 94 and everything liked it soft, lps, sps fish.. the thing is not all flow rates are the same, mine was a very dispursed flow and my rock work created regions of lower flow for the softies.

Steve

the problem with the powerheads that rotate are they are the typical pressure washer style, very high direct flow, not disperse like a seio, korilla or tunze.
You could look into one of the wavy sea units as they will help with the disperse flow and move random water around.