Coral Tank from Canada (1350gal Display Tank)

[ReefingBuddha]

I would agree with rocketiengineer in that a gyre is definitely the most efficient flow for a large tank for a number of reasons and is what I use in my relatively tiny 300g. In my application the gyre direct is changed every few hours and has variable intensity. As this is a L shaped tank a true gyre would most likely not be possible.

It would however be possible to have 2 closed loops that feed and return at opposite ends of the tank. When one is running all water in the tank would be moving from the left output to the right intake and be recirculated to the left end output again. In this way all water in the tank would be moving from left to right. If your overflows are located at the ends then all water in the tank would be constantly pushed towards the overflows. It seems logical that this would produce a similar effect to a gyre in a rectangular tank in that the momentum of a large volume of water moving in one direction will move water around it in that direction as well. The other closed loop could be hook up to push water in the opposite direction. Every few hours the direction could be reversed. As in my tank, the more turbulent transition period between one direction and the other does a great job of pulling detritus up into the water column to be skimmed out.

The old standards which calls for "turbulent" or "chaotic" waterflow are really conceptd which are past their day IMHO. Anyone who has been on a reef knows flow is not random or chaotic and the attempt to create such an artificial environment requires more equipment and therefore is less efficient and more complicated that the alternatives. This it not just my opinion, in the last few years the trend towards gyre setups for efficiency and more importantly effectiveness has been detailed in a number of articles. Im sure I can dig the up if your interested.

Looking forward to seeing whichever direction you take. Best of luck and happy reefing!

 

[Luckylouse]

Peter,

I Do NOT have a large tank. It's a 150 Gallon custom system but the flow in the tank is extreme. With 2 MP 40s and a Red Dragon 6.5 I'm putting out 7200 GPH Flow. The power heads are always ramping up and down so the flow varies all day long. When they are going all out the water flow is very intense. The SPS Love it.

I'm not sure if MP40s is the way to go but you should consider them. As you know, Closed loop systems are complicated and with all of the turns and bends and requires huge amount of pressure. I'm sure you will figure it out but you should consider some of these low profile pumps in certain areas.

The Tunze is a great option but I just don't like their appearence. If you are running the Profilux the Tunze should really be considered because the Profilux replaces the controller and gives you an immense amount of customisation.

Just a few thought.

 

[ReefingBuddha]

Come to think of it I also use a gyre in the 40g frag tank, 120g mixing tank, and 25,000g pool. More fun to swim against a current. Feels like a lazy river if you jump on a pool float with a beer.

When flow enthusiasm goes to far.

 

[mr.wilson]

Now the question is, what is the best calcium test kit on the market? I have a Pinpoint calcium meter, but it is very unreliable and difficult to calibrate. I bought it about 5 years ago when it first came out so maybe they fixed the problem, but at the time everyone on the forums had the same problems and said throw it away. I used mine one (frustrating) day and put it in storage. After spending $300.00 on it couldn't just toss it.

Any ideas?



I've used LaMotte for many, many years and as you know they do work well. The reagents should be relatively fresh. I'm sure you know this but just in case here's how to figure out the reagents and shelf life.

http://www.lamotte.com/pages/common/pages/reaglist.html

I've also used Hach kits and they appear to have similar accuracy to the LaMotte kits. Hach does have a digital titrator, 10-4000 mg/L, for Calcium testing. I have not used that particular unit but based on the quality of their other equipment I would have to give it a nod.

Are you going with a dual chamber desiccant regenerator? After 20+ years of "eating" ozonizers I have found that dry air is important. A dual chamber will allow having dry desiccant always available.

My 2 cents worth(possibly inflated)

Greg

Thanks for the $0.02 installment. We went with the same Ozonizer that RK2 rebrands as their own. It has an automated heater that regenerates the desiccant within the unit. It has a timer that kicks it on as needed. It's double the ozone Peter needs, but it will be on an ORP controller so it will just cycle on for shorter periods of time. The smaller units don't come with built-in dryers. I use the 0.3-0.5 mg/h per gallon of system water rule of thumb. http://www.cleanwaterstore.com/OS000260-p-clearwater-tech-CD-AD-ozone.html

 

[49.35 North]

Peter,
Your new found friend is indeed a chiton more specifically the Cryptoplax larvaeformis or flexible chiton. Here is a link with some pictures of it for comparison.
http://www.poppe-images.com/index.p...&fullspecies=Cryptoplax larvaeformis&catid=53

Regards Rainier

Ranier - thank you, thank you, thank you. For a snorkeler in the Philippines this is outstanding.

nineball - thank you, thank you, thank you. As everyone has already said, an awesome thread. For a complete nube it has been hugely educational, but the really impressive thing is that it seems to be engaging and helpful for everyone from the most ignorant to the most knowledgeable. That's a tough trick to pull off.

 

[mr.wilson]

just wondering have you tried closing all the ends in the tank and leaving just one open just to see how much flow your actually getting to the tank before it hits all the T's and openings? Have you tried running the pumps with no plumbing hooked to them just to see what they can do before you restrict them? Could it be to restricted on the suction side?
Terry

I've been out of town for a few days, but was able to make by Peter's today. The two 1 HP pumps are severely restricted. I would guesstimate it's getting 3000 GPH. It should be 5 times that amount but there is a lot of back pressure caused by the two mechanical filters, and the three 1" ports the water have to escape through. On top of this, the water splits into a cross (4 ways) right after being reduced from 1.5" to 1". The two pumps also share a 1.5" intake hose and a 1.5" return line so there are limitations coming and going.

The two spa pumps are energy hogs, have a lot of heat transfer, are noisy, and on;y last a few years in saltwater so we are waiting to hear back on some DC pump options. The ill-fated Red Devil by Royal Exclusive was recalled and there are a few upgraded versions out there but they are yet to be released. They may be available for MACNA, but there are usually waiting lists for such products and I assume they need to send some out to Red Devil owners first. Here is one option... http://www.aquaforte.nl/scriptsE/Blue_eco_pumps_E.html

 

[mr.wilson]

your piping on the return line should be the same size as the outlet of the pump never larger,if you have run larger piping you can obtain some pressure by adjusting valves to get a little more pressure a 1hp pump should be more than enough.
what you can do for a test is attach a flex line (braided pvc) with no valves,just direct to your tank and see what the flow is like.( you will find a use for this hose later)
there is a local person to our area,hes an expert with fluid dynamics,he may be of some help to you.( i have no acces to his number till tomorrow afternoon.)
his company name is called the hose doctor,i can get you the number if you cant find it,not sure if hes got a website.
if you do find it tell him vic from menufoods refered you,
you can also contact regional hose
they know there stuff as well
hope this helps some.

vic

Yes, this is the same test I recommended earlier before I came on board. It makes sense to test pumps on a short run to cut out all of the friction & head loss. The 1HP pumps are performing as expected, lots of volume but weak on pressure/delivery. The tank was only 6" deep when I was there and the two 1HP pumps couldn't pop the bubbles on the bottom (3" below the exit ports) or move the surface water much (3" above the exit ports).

I'm confident that we would get 10,000 GPH out of the two pumps combined once the plumbing was redone, but the brushless DC motors with variable speed control are enough of a performance enhancement that we can't ignore them. Even 3HP Iwaki MX pumps would be worth the swap for the peace of mind that they are run-dry protected chemical pumps that operate at 50-60 db (same noise as Iwaki MD100RLT). Magnet-coupled chemical pumps are triple the price of direct drive pumps, but they last 10 times longer and they won't flood your house. http://www.iwakiamerica.com/Literature/MX/MXFaxspec/MX403Spec.pdf

 

[mr.wilson]

Are you still going to be using miracle mud?

I'm not sold on the idea of Miracle Mud, but I don't see a problem in using it for Peter's tank. We will be using 200 LBS of it with the mangrove trees. It costs about $100.00 for a 10 LB bag, so you can do the math

 

[mr.wilson]

This is a great thread and I appreciate you sharing your experiences with us fellow reefers.

As for the closed loop, you are using 1hp pumps so I'm assuming you have a lot of smaller return points. Perhaps it would be better suited for less return points but make the outlets larger. When I was looking at pumps 1hp and larger they all seem to drop significantly with head pressure. You want more flow, then reduce the head pressure. I think larger openings could possibly do that.

Also on another thread I was reading they designed the closed loop to try to move the water at the upper levels of the tank. They stated that the bottom would follow the top water.

The nice thing about closed loops is there is zero head pressure (head loss) because you are sucking and blowing from the same height. You do however experience friction loss as you go through tees, elbows, mechanical filters, a chiller, UV sterilizers, leaf basket, valves, reducers and shared in & out lines.

Our plan is to open up the breathing both in & out, and at the same time switch to pressure rated pumps. Even after the water has made it through the pipeline it's nice to have that pressure to shoot across the tank, moving additional water with it.

You are absolutely right, you want to move the low oxygen water at the bottom to the air/eater interface at the surface for gas exchange. Very little gas exchange occurs in protein skimmers and the flow through is dramatically slower than the turnover ratio and surface area at the top of the display tank.

My laptop is dead so I'm trying to update the flow drawings in the next day or so. The basic idea is to move sump return water from the center (90˚ corner) of the tank to the two overflows at the opposing ends. We will be using swirl-type wave devices at the surface to get full coverage of the 36" wide tank and to create some ripples, better surface turnover and coral swaying. The closed loop pumps will be on their own segregated lines as two zones. One pump sucks from one end of the tank and blows at the other. This way the two pumps are constantly exchanging water from one side of the tank to the other. Keep in mind, one length is 16' long and the "short end" is 8' long. The closed loop returns (outs) are spread across the bottom
and will pass water from the two ends toward the middle of the tank along the bottom. Once the water hots the corner bend (middle) it gets shot up to the surface by 45˚ elbows to complete a circular flow dynamic. In summary, water goes across the top from the middle to the two ends, then down the end walls and across the bottom to the middle where it completes the loop as it shoots upward. Of course the rock work changes all this, but you get the idea.

It's will be a lot easier to follow with the drawing.

 

[mr.wilson]

Peter, I'm not sure I understand when you say you want your internal closed-loop system to produce "chaos." Certainly, the internal system is supposed to be your prime source of water movement within the tank, but if you set up a gyre (which Mr. Wilson is quite familiar with) there shouldn't be a need for excessive turbulence/chaos. Since you've never actually published your plumbing schematics I think it would be pretty hard for the more knowledgeable people here (not me) to venture opinions.

Dave.M

I agree "chaos" is a poor flow dynamic. That's what you get with powerheads and an uninspired timer. A good gyre/laminar flow or circular flow will keep the water moving with momentum (kinetic energy/inertia). As long as detritus is kept suspended it will float around feeding corals from all angles like a snow globe. There will always be a basic pattern that forms and there will always be variation and randomness as opposing forces meet and water swirls around.

You need method to your madness with flow dynamics. The most efficient systems pass detritus from one exit port to the next just like sweeping a floor. Eventually the detritus makes it to an open coral mouth or an open drain to the filtration system.

Where the need for "chaos" gets exaggerated is where coral growing patterns form. If the water flows in one direction, angle and velocity on a constant basis, corals will adapt to feed accordingly. This is where survival of the fattest causes corals to grow like bonsai or long straight branches on SPS.

 

[jjk_reef00]

Wow that sounds very exciting, I can't wait to see the drawings!

 

[mr.wilson]

something else to help with flow not sure if you've already checked these but i've seen these really help with adding to the flow

http://www.marinedepot.com/Pacific_...s-Pacific_Coast_Imports-FT0033-FIFTFB-vi.html

flow wise i've always thought it's not so much how many gph your moving but more how the flow is being used. Especially in a tank like yours i think your biggest problem will be trying to keep detritus in suspension long enough to get to the overflows and be skimmed out of the tank. To add on to what vic said i think it would be better if you measured where the corals would be. A streams not a problem as long as it's not blowing into the coral or the sand bed. The fish will move out of the way. I have a few tangs that like to swim right in front of the powerheads like there on a treadmill lol.
Terry

Absolutely! Penductors, eductors, and flare nozzles like this one create a venturi, drawing more water from behind it. You can move more water without increasing the amount of water going down the overflow drain or flowing through the closed loop lines.

One of the benefits of powerheads over closed loop pumps is they have wide spread flow so corals are not damaged and dead spots can be minimized. The device you linked is one of the ways you can achieve this effect without losing the many benefits of closed loops. Keep in mind, powerheads move water from one end of the tank to the other, while closed loop pumps move water at both ends of the tank as the intake can be at the opposing end. That's 24' away with Peter's tank. If you use flow control valves like Oceansmotions and variable speed pumps you can create any kind of wave action with no moving parts in the water and no ugly powerheads or cords.

Closed loops took a beating when hobbyists decided that it was worth spending $1000.00 to save $30 a year on their electrical bill. The new DC pumps level the playing field once again. Closed loops allow you to locate the in & out lines at any angle and any location you wish, while the best powerheads on the market (Vortech) are limited to the end of the tank in the middle (not close to the surface and not close to the bottom), pointing directly outward across the tank. Angling the exit ports slightly upward moves water toward the surface and creates a rolling/swirling effect that keep detritus suspended rather than pushed down into the rocks & substrate to decay.

 

[mr.wilson]

The amount of flow required definitely depends on what you plan on keeping in the tank. Since I have a feeling there will be plenty of SPS, too much flow is not as much of a concern in my opinion. You just want to make sure that corals are not placed in the direct flow if it is a high pressure stream. Of course, you also need to take into consideration that flow dynamics within the tank will change over time, especially when the corals start getting large. Make sure that is in the back of your mind when figuring out the flow. It is a good idea to have a vision of how the rock formation will be laid out when designing the plumbing in my opinion, otherwise you work backwards and have to design the rock layout around the plumbing. In this case I think that may be what ends up being done, but I don't see a problem with it.

You have mentioned chaos several times. Have you considered talking to Paul over at Oceans Motions? As far as chaos in flow goes, I would think he may be a great person to talk to. Can't remember where I saw this, but I don't think it was here. Definitely a hint of chaos there - "That'll do" :thumbsup:

Did we decide that surge tanks are not a possibility with the overall design? A nice surge at each end would really create some chaos :smokin:

Yes, we are trying to get paul from OM in to advise on some wave making devices. He has a prototype swirl-like device that uses his 4 way body & motors. The benefit of his device is it can operate with back pressure so penductors can be used. This isn't an option with Vertex, or Sea-Swirl models.

Unfortunately, we are limited to 6 holes in the bottom of the tank for a closed loop. We need two fro intake which leaves 4 for returns. This doesn't lend itself well to much other than a 2-Way wave maker that would spilt flow back and forth between two ports. We will already have variable speed pumps so it may be redundant.

The ideal device for Peter's application would be something that changes the direction of flow to alternate each port from sucking to blowing. Thus way the intakes will be self cleaning and waves can be created like in the video. You don't need a lot of flow to create waves. You just need to time flow so you catch the wave.

More on this as we continue to scratch our heads and various other body parts.

 

[mr.wilson]

I am not a big fan of closed loops for larger tanks. I had a couple of hammerhead pumps on a closed loop in a 10' x 4' tank with about 8 nozzles and I could barely feel a thing from each nozzle. Ended up replacing that with a few tunzes and the difference is amazing. I can also now adjust the flow as the corals grow not to mention the electric bill savings
I just think they work better on 4 - 6 ft tanks.

I agree, Hammerheads are useless for aquarium use. They are anything but energy efficient, way too loud to have in a home, and fail to deliver pressure. The are the best of the worst (direct drive pumps), as they have premium silicone carbide seals. They only last 5 years in saltwater applications because they are not chemically rated pumps. It's like blowing out a tire. It could happen while your car is parked or while you are passing someone on the highway. As Reefski can attest, it isn't fun when your pump blows a seal right out.

I don't know how long this generation Tunze's will last with constant cycling on and off, but I doubt they will last over 10 years like an external chemical pump will. Sometimes energy savings are penny wise and dollar foolish. I will admit I'm biased because I've been shocked so many times by the older generation powerheads and I don't like seeing gadgets in the water, but many people don't mind. The low voltage aspect has brought powerheads back from the dead. Controllability has also gained them a bigger share of the market, but it isn't fair to compare a cheap closed loop pumps like Sequence to premium powerheads like Tunze.

 

[killerbee181]

Yes, we are trying to get paul from OM in to advise on some wave making devices. He has a prototype swirl-like device that uses his 4 way body & motors. The benefit of his device is it can operate with back pressure so penductors can be used. This isn't an option with Vertex, or Sea-Swirl models.

Unfortunately, we are limited to 6 holes in the bottom of the tank for a closed loop. We need two fro intake which leaves 4 for returns. This doesn't lend itself well to much other than a 2-Way wave maker that would spilt flow back and forth between two ports. We will already have variable speed pumps so it may be redundant.

The ideal device for Peter's application would be something that changes the direction of flow to alternate each port from sucking to blowing. Thus way the intakes will be self cleaning and waves can be created like in the video. You don't need a lot of flow to create waves. You just need to time flow so you catch the wave.

More on this as we continue to scratch our heads and various other body parts.

What about bringing some of the returns over the top instead of just the bottom it could also give more control of flow especially with a wave making device. Then you could even use 2 more of the bottom holes for drains for 2 more pumps if they where needed.
Terry

 

[mr.wilson]

I was also just thinking that propeller stream-type pumps may actually be a better choice for water movement in a tank this big than a closed stream set up.

Have you and mr wilson considered the Tunze Masterstream pumps?

That is a great pump for a large tank, and as much as Peter's is big, a lot of that size is length not width or height. That would be my first choice for a tank over 3,000 gallons for sure. In a tank that big, you don't have anemones and shrimp etc. crawling around the pump intake. You can mount the pump in a conspicuous spot away from critters without it detracting from the view.

Moving parts in the tank are a bad idea. The Masterstream has a large intake strainer, but I would still build an eggcrate cage around it for a public aquarium setting.

 

[mr.wilson]

Also, have you see what some of your other fellow large tank owners have been pondering for flow?

http://www.reefcentral.com/forums/showpost.php?p=16486228&postcount=368

I like that one as well, but again, for a public aquarium. If we were starting from scratch, we could build these into the two ends of the tank to create a laminar flow. One would suck at one end and the other would blow at the other. You would need a huge pipe to accommodate them but you could make tidal waves

 

[mr.wilson]

Hi Peter

I would be more concerned about flow through the tank than the "pressure" of the flow coming from the outlets. Without knowing too much about your plumbing, I think "head pressure" would seem to be reducing the efficiency of your pumps. Pushing the water up in to the tank is not adding to head pressure, as this is negated by the fact that the pumps are effectivley being gravity fed by the tank. Therefore the only thing increasing the head pressure is the plumbing itself, smaller diameter pipes will increase the speed of the flow, but also increase the head pressure. Keeping the size of the plumbing as large as the outlet of the pumps you are working with, the inlet diameter ideally larger, reducing the diameter only after it is tee'd off will help to keep the head pressure down, using 45's instead of 90 degree bends would also help, every bend in the plumbing will also add to head pressure, as will putting nozzles on your outlets, maximum flow will be more important than decreasing flow to increase the speed of flow from the outlet.
I'm certainly not an expert in fluid dynamics, just the research that I'm applying to my build.
P.S. - As long as you're being open minded to all plumbing/flow options at the moment, I have purchased 6 Tunze pumps for my 1450l (375 gal) tank to give me a potential flow rate of 108000 litres (28500 gal) an hour, or turning over the tank volume about 74 times an hour (way overkill, but the potential's there). These pumps can be controlled to work on alternate flow between the pumps, so you're only using about 50% to 70% of the collective pumps flow at any one time (I'm sure you've noticed these on Chingchai's tank!)
Sorry for the long post, it's not too often I feel I can add to the constructive process in this thread, but I hope this might help.
Cheers Ben :beer:

We are shooting for 25,000 GPH to get a turnover of roughly 20 x (depending on how you count rock displacement and actual flow etc.). The standard for large tanks drops off quite a bit from that of "standard aquariums". Tank height, fewer dead ends (longer runs) and more open areas decrease the need for higher flow ratios. In other words, 20 x flow ratio in Peter's tank is equivalent to 40 x flow rate in a 150 gallon tank.

I agree, it's nice to have "too much flow" available and dial it down most of the time. You can turn it up to "11" every few days to free up trapped detritus in the rock work and slough off (shed) coral mucous.

 

[mr.wilson]

I'd like a better idea of your expectations. I don't recall if you ever mentioned using wave boxes or Tunze or if you want the closed loop system to supply most/all of your water changes. If so, you're likely undersized, although we've never seen detailed pump/piping specs so it's still hard to tell. If your looking for the closed loop to handle 20 turns/hour, it would require a pump and plumbing capable of 27,000 gals/hr or 7.5 gals/sec based on 1350 gal tank. With 1.5 inch Schedule 40 PVC pipe, that would require a flow rate of 71 ft/sec. Even if your pumps can handle that, at those rates, every elbow and fitting is VERY significant. And cross your fingers that you never have your piping burst, you'd empty your tank in 3 minutes.

From looking at old pics of your tank and listening to the issues, I do think you have piping issues. You have piping that enters the bottom of your tank and then tees and tees again to create 4 outlets for each hole you have in the tank bottom. The thing that first caught my eye when you first posted the pics was that the piping entering the tank bottom is the same size (maybe 1 inch PVC) as the 4 outlets that it tees to. Therefore, whatever flow you had coming into the bottom of the tank is cut to 1/4.

I'd be very interested to see the pressure readings if you put a pressure gauge just after the pump outlet. If your pressure is higher, you're restricting your flow with your piping too much, if it's very low, then your pumps are undersized for what you're looking for.

What are the flow ratings for the pumps you have currently? Those numbers are pretty accurate and should fit into your equations well. Beyond that, it's plumbing. Every elbow, valve and union causes loss in flow, especially if your piping is undersized.

However, I think you're better served by offloading some of the flow requirements to waveboxes or Tunze rather than creating an industrial pumping system. If you do go that way, invest in monitors and automated valves that can shut things down of your pipes burst. Use the closed loops to put flow in the hidden areas of the tank that other methods can't reach.

We are going with a closed loop for two reasons.

1) That's what the tank was built for.

2) While Peter doesn't have a problem with powerheads showing, we want to be able to make as much flow as we want where we want it.

Powerheads use much less energy than most closed loop pumps, but much of that flow is inefficient as it bounces off of opposing flow, rocks and aquarium walls. Powerheads are often placed at the top of the tank randomly with little or no thought put into their placement. You can do it, but powerheads are rarely used to move water from the bottom of the tank to the top for gas exchange and detritus collection. Typically they bounce flow off of the viewing panels which causes algae to grow and sand to be displaced. If you engineer them properly, powerheads can create circular flow and even somewhat laminar flow, but this is the exception not the rule. Typically, they fire detritus deeper into the sand and into the voids of rocks.

A powerhead rated at "1800 GPH" doesn't actually move 1800 GPH through the impeller. These are nominal numbers provided by the manufacturer that may include the water that is subsequently moved by the water travelling through the pump itself. A closed loop pump will have a true rating of what exits the pipe. If 1800 GPH comes out of the pipe at one end of the tank, you have another 1800 GPH being sucked at the opposing end. Now tune these two ports so you have minimal friction between point A and point B, and you have a number greater than 3600 GPH. A powerhead does draw water in through the back of it, but it isn't activey pulling water from the opposite end of the tank. Water will hit the end of the tank and bounce back and water will migrate back to replace the displaced water, but you don't have the kind of kinetic energy you get when you stir a bucket of water for example.

 

[mr.wilson]

I have been following this thread for a while so let me throw in my comments. Flow in large tanks seems to be much different from flow in small tanks. In a large tank, bulk water flow seems to work better as the size of the tank allows currents to be developed that would be impossible with smaller tanks. This being the case, the gyre style would be better suited then a bunch of small outlets. Consider the case of using a flow rated pump (Reeflo Super Dart Gold) combined with an OceansMotions 4-Way with a Version 3 drum, you would be able to have a section of the tank have bulk water flow in one direction and then switch it to the opposite direction. If you were to employ two such setups you would get ~4300gph*2 = 8600gph for a max of 350W where using a hammerhead would flow a max of 5800gph while using a max of 375W. In this scenario, using two smaller pumps will gain you more flow for about the same energy usage. Since you are looking at closed loop the use of two pumps over one means you can take one closed loop down for maintenance without shutting down all flow in the tank.

Eductors are another way to go for gaining bulk water motion. However, to function properly they need a pressure rated pump rather than a flow rated pump.
http://www.kthsales.com/website/Misc/hello_salt_water_enthusiasts.htm
The eductors mentioned work best at about 23' of head with 7gpm which means a MantaRay would be able to run 10 of these. Given that each eductor will pull 2-3 times as much water into the outlet stream as the pump provides, you will be looking at something like 12600gph for 900W.

Given those scenarios you get:
1) (2) Super Dart Gold + 4-way= 8600/350= 24.6 gph per watt
2) Hammerhead + 4-way = 5800/375 = 15.5 gph per watt
3) MantaRay + (10) eductors = 12600/900 = 14 gph per watt

Based on this crude and definitely WAG calculation, I still think that several efficient low-head, high-flow pumps combined with motorized wavemakers would result in the most turbulent flow for the least daily cost. If the openings exist, using two or more separate closed loops and having the 4-ways on timers/controlled would mean that semi-random flow patterns can be created within the display by varying the times that each outlet switches throughout the day. An example would be to have the controller turn off the 4-way on one pump for an hour at noon, turn off a different 4-way at 6pm, and so on. Since you wouldn't know which outlets the 4-way was directing water to at the time of shut off you would get equal chance of either direction but during that hour the flow would be predominately in one direction while the other pump creates turbulance against this bulk flow.

Just a crazy idea I have been throwing around for a dream system.

RocketEngineer

Now that's what I'm talking about. Here I was getting ready for 20 posts challenging my opinion of closed loop systems vs. random powerheads, but I know I have one proponent at least

People get caught up in electrical consumption and GPH without looking at pressure, venturi effect, and dynamic flow. You hit the nail on the head with "bulk water flow" in larger systems. Once you get a body of water moving it is a powerful thing. The area of focus should be on what that GPH rating does for you when it exits the pump. If it can sweep up detritus, move water to the surface and take with it as much subsequent water as possible than you have efficiency numbers that trump energy savings.

If the DC pumps work out as they promise, we get 11,000 GPH @ 1500 watts. Those numbers may not compare to some powerheads but that's harnessed power, rather than raw power. We can aim it anywhere, locate it anywhere, have one feed another, change direction of flow in the pipes, and change the velocity for pulse or surge cycles.