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continuing thoughts on water flow

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from my post in animalmasters thread



as to flow. start with turnover stupid way to figure out flow. a better way is distance over time by width. why do i say this. hmmmm


things like vortech, koraila's, moded mj's are a vast improvement not only due to greater flow but there wider flow. why this helps move more water. as the water flows through the tank it begins to move water along with it. due to the fact that water is well sticky thus helping to increase overall water movement. ah ha i think we may be on to something here use the water we move with the pump's to reinforce and add to the movement. this can be done a couple of ways that i know of. harmonics (aka vortech's) or pressure induced compresson followed by a release (aka eductor nozzle's and yes i know you cant compress a liquid just trust me). idealy you shoud take advantage of both. the trick is knowing how to best use each. now the eductors are easy, put them on the return's from your sump and call it good right. well half right, the other half is understanding how the out put and input are related. thus what they need based on this. room for the out put to expaned and the input side to be unrestricted. so somewhere along the back of the tank, a little ways in from the back. but not stuck in the corners restricting flow to the intack side angled at the corner should work out. so maby a foot or so in from the corners. if you could get the output from these two nozzles to switch back n forth that would be even better. now i'll bet there's a way to do that. now they work best with a strong or presure rated pump(which is why switching back n forth is usefull to this pat of the planing. it keeps the presure up), but they will still work with any pump. on to harmonics, have you ever heard of room modes. places were the bass gets really boomy or suddenly its just not as loud. this is harmonics. waves bouncing into each other and eithor reinforcing or negating the energy carried buy said waves. once the waves are genreated it does not take much to keep them up. think of a pendulum, pull it back and let go. it will only come back to a certain pont, to enable it to come all the way back it needs a little push on the other side. this is what vortech do they give the child on the swing a push to help them mantain the size of there back n forth motion. dosent take much once its going. just makes getting there faster.



so would say return pump with two out puts swithing back in forth with eductor nozzles. mated to a vortech at each end. would be one of the ways to go at this point.



so now that we have that figured out what are we going to use it towards, how should the water flow idealy. mmmmm.....


the best thing to use this flow towards is called a gyre. basicly a fanciy word for water moving in a circle. ths helps move the water near the surface to the bottom and vice versa promoting all kinds of good things. such as detrus from ever reashing the bottom of the tank, gas exchange, waste removel for the corals and so on. now to do this one must minimize the amount of contact between the sides of the tank and well anything. hmmm... so what does that mean. that this is were we see the unintend perks of the move towards bonzai aquascaping. minimizing contact between the rock and sand improves flow through reduced turbulence near the bottom of the tank. which if we can learn any thing the barebottom era is the secret to minimizing waste aqumulation on the bottom of the tank. now i know someone's going to say but theres sand its ok. doesnt matter if its a bare bottom tank, shallow sand bed, dsb, dsb with plenum. there all the same thing the bottom of the tank and the tank will be better off if you keep it from having "stuff" all over it. keep it in the water colomn and move it to the skimmer were it belongs. this is why we want water flowing in multiple derection to help prevent dead spots while moving water from the bottom up.




hope that helps

rember flow is more important than light, flow is breathing while light is eating.


forgot to mention induction zones work to maximize the size and duration of the induction zone when ever posable. any way talk more about it later.

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the basic equation for velosity of water through an opening ( hole)


v = 8 x the squar root of the height of the water ft/sec



the rate of flow (speed of flow through a hole this size)


rate = A (area) x v (velosity)


rate = 8 x A x the squar root of the hight of the water x ft cubed/sec

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Nice thread! I'm currently doing research on improving my flow in my 60g cube. I see that both a gyre and oscillating motions are recommended. Its rather difficult to do both, impossible at the same time. The minimum frequency of oscillation depends on the mass of the gyre for a given power,.. roughly.

Do people use slowly changing gyres? (this seems the best from my reserach 'so far')

rapid oscilations? ala vortechs.

steady gyres?

large steady gyres with high frequency perturbations?

And if you use one of these, how has it turned out for you? How would you set your tank up if you could do it over?

Thanks in advance!

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i agree. I have 65x turnover in my tank but still have dead spots. Total movement at a reasonable intensity would best replicate the ocean right? 10 tiny powerheads?


how about that crazy wave-box video we've all seen ?

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I think the best water movement would be a back and forth at 0.1hz to 0.3hz, just basing this assumption on what i see in shallow coastal zones. That 1hz oscillating wave box is CRAZY, I would really worry about the strength of my tank with one of those!!!! Plus it just looks wicked unnatural to me :)

I'm thinking about hooking up a large pump to a SCWD and having each section output along the length of pvc, so that the flow is being even directed along the entire depth of the tank, instead of from a point as most power-heads and nozzles do. In other words, a submerged spray bar mounted vertically. My main concern here is all the head loss I'd receive from the SCWD and the spray-bar config. What do you think of this?

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my current setup use's a scwd, for the smaller tanks like we use this is an exallent option. the head is not that bad but the speed is dependent on gph, and to create a good gyre requiers lower gph than you would expect. which is why i run the returns though eductor nozzels. and yes multiple outputs to help from the gyre at diffrent points in the water coulum makes a noticable improvement. keep in mind that the rock scape has great inpact on the patter of water flow. also the position of the overflow is significant, this is the largest problem in my current setup.


in my setup the gyers are establised for ruffly 5 sec, with about 4 sec of induction. the scwd switches at around 8-9 sec. its hard to time it exactly. but its running @ about 382 gph. based on the math.


is there a link to the wave box.

Edited by bitts

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this is the wavebox video i think cruiZe is talking about..... is it cruiZe?

Do you have a tank thread bitts? If so could you post a link?


My current aquascaping consists of a tall tower in the center of a 60g cube. So i want to have a clockwise, counter-clockwise gyre. 5-10 seconds between direction changes would be really great. do you have any great ideas or links on how to do this?

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flow chart for 3/4"scwd.


Flow into SCWD SCWD TD Output Efficiency Switching Duration

150 gph 90 gph 60% 22 seconds

180 gph 120 gph 65% 16 seconds

240 gph 180 gph 75% 12 seconds

270 gph 210 gph 80% 10 seconds

330 gph 240 gph 80% 9 seconds

400 gph 360 gph 90% 7 seconds

600 gph 540 gph 90% 5 seconds

720 gph 660 gph 90% 4 seconds


tank thread is in my sig.

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Of coarse it's in your sig! :slap:

I actually already have a 3/4" scwd just sitting around doing nothing right now. the problem is that at, lets go with 10s for now, i can only use 270gph. I'm also not sure how much it takes but I'm highly suspicious that this isn't enough to create a gyre in a 60g. And if I used two or three they would quickly get out of synchronization due to small fluctuations in their period.

Maybe a 1" scwd with a huge pump is in my future.

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Actually a 1" scwd will NOT be in my future. The switching times are MUCH to large! The fastest is 30 seconds at 3500gph!!!!!

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now this would be neet

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from DHaut's 40 thread


I just acquired a 40B and I would like to do a corner overflow with herbie-style drain and a back return.


I've briefly looked here: http://www.nano-reef.com/forums/index.php?...p;#entry2890605


My questions:


1. What size holes do I need for the drain and the backup?

2. What size hole for the return?

3. What pump recommendations? (I'll be running an MP40 for the main tank flow)

4. What plumbing parts do I need to pull this whole thing off and where's the best place to get them?


I'm a total noob with tank plumbing, so any help is appreciated.



What size holes do I need for the drain and the backup?


1.) To start there is a relationship between drain size & flow rate. Flow rate is acheaved by the height of the water line above the drain, combined with the size of the drain. I.e. The more water & the larger the drain, the greater the flow.


2.) How much flow is wanted through the sump/fuge. There are great debates over what is the ideal flow, but a fuge needs a high dwell time for nutrient transfer. So maby, as much as it pains me to use the term, 5xthe size of the fuge for turn over. Flow can be met by powerheads. Simple sumps have no limitations on there flow behyond micro bubbles, heaters, & skimmer performance.


In the over flow thread there I have a link to a flow rate calculater. I'll see if I can add the link here with the blackberry if not will do later.


3.) More than likely it will be either a 3/4" or a 1" drain, pearsonaly I like to use the same size drain for both drains. But here's that relationship coming back. As you move the drain closer to top of the tank, the less flow it can handle. So the backup has to be able to handle grater flow than the primary if & when the the drain clogs (Yes the drain will clog). This helps to set where the drains will be Placed. The distance between, height within the overflow, & so on. The back up needs to be low enough to drain while still not having the overflows water line go above the weir (you knew I'd work it in there some how, fancy word for were the water flows over). While the primary needs to have enough distance between its self & the backup to be fully submerged with out creating a vortex sucking bubbles into the drain (that's what makes noise).


4.) When drilling tanks. There needs to be, at minimum, the diamiter of the hole between the hole & the edge of the panle being drilled. This is the minimum to not crack the glass. More is better.


So figure out how much you want through the sump/fuge. Then put the backup as close to the weir as you can & still achive this flow. Then put the main as low as you can with out cracking the tank. Set water line in overflow with ball valve or gate valve.





What size hole for the return?



1.) This will most likely be the same as the output of the pump. Would expect 1/2" or 3/4".


2.) 3/4" or 1" return plumbing can be split then reduced to 1/2" as it enters the tank.


3.) Without siphion brakes, or other messures to prevent backflow. The tank will drain to these returns when the pump is shut down.




What pump recommendations? (I'll be running an MP40 for the main tank flow)


1.) Normally the least expensive to run. I hate spending money I didn't need to.

I run quiet one pumps for this reason. But to be dead silent eheim is supose to be the best. Untill you steep up to exo's like iwaki (the pretty japaness one) or gen x (the knock off)


2.) Eductor nozzles can reduce the size of pump needed to reach a set flow rate without effecting the drains. (Free flow)


3.) Never reduce the flow to a pump this will cause the pump to cavatate (bubbles).


4.) When picking the pump remember to judge it not only on flow rate but head.





What plumbing parts do I need to pull this whole thing off and where's the best place to get them?



1.) Welcome to the never ending trips to homedepot. Most plumbing will be found at the local box store. Speicalty items like bulkheads will be at the lfs.


2.) Peaces parts

Vynal tubing

Hose barb fittings (sevral types. 90? Mpt for the main, reg mpt's for most everything else)

A couple feet pvc

Teflon tape (this is your new best friend. Use a lot & once you have tightend the fitting will need to be replased if lossened)

Bulkheads & screens (no open pipes)

Pvc solvent

90 elbows & other pvc parts

Ball valves/gate valves

Quick conects/true unions



3.) Air leaks cause asperation (bubbles) make sure to have all joints sealed tight







There are pics of my old ten x ten in my tank thread & more info on water in my sig.


Hope this helps. Pm me when there's more questions.

Edited by bitts

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Evolution aquascape in my ten x ten to improve flow.










pics of the diy herbie







drains are 1" controlled by ball valve below.

Edited by bitts

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To define overflow

+1 to luvinmyacans

Overflow = water flows over to the drain. Where this happens is called a weir. There are 2 types with sub types there after. Internal & siphon based. internal is a wall that water simple flows over. Siphon type is normally referred to as continues siphon overflow, where the water flows up & over the back of the tank. When the siphon fails the tank overflow, or in properly design setups you run the pump dry.


Sub types of internal overflows.


Standard issue 2 or 3 sided internal glass wall. (Tried & true)

Calfo coast to coast.

External coast to coast.

Pvc coast to coast.


These all drain based on gravity. Even the siphon based (siphon simply moves water to the drain.)


Next comes drain types.

Starting with stand pipes(loudest), stockman, durso, moving up in complexity & sound level to herbie & bean(dead silent). All have a place & use.


As the drain enters the sump/fuge it is useful to run it through a hartford loop to remove any last bubbles before they enter the sump. This causes noise & salt creep.



Drain placement is based on hole size & depth. See my water flow thread for a more detailed explanation & flow calculator.


Drains will always clog. Not an if but a when. Therefore use a back up. (Herbie)




Drilling two schools, hole saw & dremel.

No matter which type let the tool do the work. Templates or jigs made from wood or plastic help to giude the tool as you start the cut. When drilling (holesaw) renforcing the back side. This will help prevent large chips. With the dremel have found the tile cutting bit to work best.





Need an overflow to prevent the tank simply draining to this point when the pumps power is cut. Ruber washer is placed on the inside of the tank. While the threaded porton is to go outside. Bulkheads are to be finger tightened, over tightening can cause them to leak.




Propperly designed tanks lead to happy wifes & dry floors.

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Thanks big D.


Always think back to what a pian in the ass it was to find & learn this info. Thought that if you throw enough buzz word into the same thread, that hopefully it would show up in a search.

Edited by bitts

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