Coast to coast overflow hampers wave?

[banditpowdercoat]

So I've been playing with my WP-25's on my 150. Have one at either either end. Got a not bad wave, or so I thought. Today, doing some spot feeding and such, Sump return off, so the water level in DT down below the coast to coast overflow. And now I am getting like double the wave size. And seems more sway in tank. Wondering if I should block some of the overflow off??? Maybe make it in 3 sections or I dunno, just be happy with the littler wave LOL

[asylumdown]

I'm no physics expert, but with the water level lower in the tank but the pumps at the same height, they'd be relatively closer to the surface, so to me that seems like you'd see more of a wave. Hopefully someone who actually knows the physics of liquids will chime in and tell me I'm an idiot, but when you've got a powerhead angled horizontal to the plane of gravity under 7 or 8 inches of water, you barely see any surface disturbance, but when that power head is only 2 or 3 inches below the surface of water, the surface turbulence is enough to create splashing.

I also know with a standing wave the whole mass of water is moving, but I still feel like the total mass of the water in your tank, relative to the output of your powerheads, will affect the kind of wave you develop. With less water in your tank, it seems like it would be easier for the powerbeads to create a bigger wave.

The C2C is probably affecting it somewhat, because as water flows over it, it's also taking some amount of kinetic energy from your wave with it, but any overflow will likely do that.

Not sure which of those things contributes more to what you're seeing, or if it's something else completely and I just don't know what I'm talking about.

[Slick Fork]

Coast to coasts and corner overflow boxes do dampen waves considerably since they cut them off at their "height". You could play around with covering the ends and see if you can get a result you like that still allows for decent flow through your overflow.

[Wheelman76]

The closer to the surface your pumps are the easier it is to for them to create a big wave.

[Jaws]

Coast to coasts and corner overflow boxes do dampen waves considerably since they cut them off at their "height".

Do you think that decreases the wave under the surface as well or just what's visible to us on the surface?

[Slick Fork]

I think it decreases the energy level of the whole wave. If you think of the way a wavebox works when there's no overflow to deal with, it goes back and forth like a seesaw. If you cut off the top of the cycle, you lose out on all the extra energy that would be gained on the "downstroke". Real waves seem to be less about current and more about momentum, if that makes any sense. A center overflow is ideal because the wave in the middle of the tank doesn't really move up and down, almost like it's a fulcrum point.

[mike31154]

If you look at it from a 'head' pressure perspective, it seems logical that with a lower water level (less head pressure), the pumps are able to create a larger wave since they're moving less water. Not sure the overflow has that much to do with it, but I'm not a physics professor either!

When I first got my MP40s, I had fun playing around with the wave making feature, but am now content to have them run in a random mode. I only put them into wave mode shortly before I do water changes these days. Helps transport nutrients. Wave mode gets too noisy & annoying to use continuously. Livestock doesn't seem to care either way.

[jason604]

I think it decreases the energy level of the whole wave. If you think of the way a wavebox works when there's no overflow to deal with, it goes back and forth like a seesaw. If you cut off the top of the cycle, you lose out on all the extra energy that would be gained on the "downstroke". Real waves seem to be less about current and more about momentum, if that makes any sense. A center overflow is ideal because the wave in the middle of the tank doesn't really move up and down, almost like it's a fulcrum point.

+1

[jason604]

How long is your 150g tank? I was thinking about getting the new WP14000 (upgraded version if the wp40)power head for my 75g 4' would that be overkill even with a variable power suppy?

[banditpowdercoat]

My tank is 5'. Amd I think 2 WP25's isnt enough, but 2 40's might be to much at full? Not sure. I have them running off a Apex, not the Jebao controller. I might upgrade to 2 40's later. If I ever find some extra $ that this Divorce doesnt suck out of me

[sphelps]

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.

[banditpowdercoat]

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?

[Slick Fork]

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.

[banditpowdercoat]

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.

[StirCrazy]

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

[banditpowdercoat]

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