I don't think you need to be a professor to understand why coast to coast overflows and waves don't mesh well. Power heads are relatively small pumps but can generate waves by pulsing at a certain frequency that resonates at a natural frequency based on the tank dimensions, head pressure has nothing to do with it, however volume certainly does but not the issue here. This natural frequency is very sensitive, you'll notice that by changing the pulse interval slightly the wave will disappear, thus illustrating the sensitivity. An overflow box will disrupt the wave because every time water is pushed to one side a portion of the volume is absorbed by the overflow box so less volume bonces back as a result. Coast to coast or double overflows are the worst as they'll absorb the most volume as they are located on the far side on both sides of the tank and therefore the wave. Besides no overflow at all, center overflows are the best for generating waves so blocking off both sides of the coast to coast will produce a noticeably bigger wave.

Now my conundrum. Tank level is fairly high. Built it before I went with a wave. SO I have 1.5" static water height between my overflow and Eurobrace. I can lower it about 3/4" as I have a plastic top strip all along my weir of the CtoC overflow. But, i'm trying to weigh the pro's cons here. Lowering the water level 3/4" and kinda making the CtoC into a center overflow isnt that bad, But if I dont like it, going back to full CtoC will be a chore. Would the better wave stir up more detritus and be more helpful than the full surface skimming my CtoC overflow does now with the lower wave height?

Maybe I'm just overthinking and grasping at ideas cause of my recient Dino's outbreak and pretty much loosing all my Zoa's. I have a lot of rock, and flow in and around rocks osnt the best. All the remaining sand and detritus piles up under the rocks where I cant siphon or stir it up regularly. Was maybe thinking a bigger wave could help with that?

Personally, I'd take the bigger wave as the increased stirring up of the whole tank seems to be the bigger win over increased surface skimming.

Well I made some changes, I cut about 12" out of the center of my Coast to Coast Weir. I have a plastic extension piece above the glass. I lowered this 12" piece about 3/4" and now the wave is bigger, It sometimes just flows over the original height, but just a tiny bit. Most is flowing in the center cutout. I'm liking it more now. A bunch of water changes, scrubbed all my rocks, removed as much built up detritus as I could reach and using Carbon seems to have lessened the Dino's Not gone yet. GFO should be here tomorrow, as well as a new clean up crew to restock. Some Zoa's still left, but there all closed with little strings of Dino's out their heads. Hope they can fight it and survive. Ric's have shrunk bigtime too, but the remaining ones look healthy and have color.

I would have left the overflow alone and not cared about the surface wave myself as long as you are getting motion below where you want it.

if I could get the motion along my rock with out the surface moving that would be the ideal setup.

by blocking off your coast to coast you are defeating why they were so good to start with.

you could always look at the flow along your rock/corals and see if blocking it off actually makes a difference or not.

Steve

That's just it, I wasn't getting the flow needed below the surface. AND, the amount of weir I lowered still allows some coast to coast overflow. But maybe 1/16" now with the wave, not the 3/8" it had all across the 60" length. So in essence, I am probibaly skimming the same surface as I was, Just the surface tho, not some depth like before. The center cut out handles the volume