What do you think is the best way to achieve flow?

[Reefbox]

I'm sold on the closed loop manifold system but am interested to what others have to say, for my next tank.


I have a Sequence Hammerhead pushing 5800 gph through a closed loop manifold and an Eheim 1262 filter loop and i like it.

[coralite]

The best way to achieve flow is to have all your outlets working together to move as much water volume . You should encourage mass water movement by using a minimal amount or rock and aiming your outlets to push the entire surface layer water of water from one end of the tank to the other. If you succeed in moving the entire surface layer of water, the entire water mass of your tank will move, gain momentum and essentially push water all over your tank where you're not even looking. Fast straight flow is more important than "random chaotic" flow. The faster the water flow moves the more turbulent it will become when it encounters a surface. SPecific use of nozzles like eductors and flares can also help you increase flow speed and move the water in teh direction you want.

[ezrec]

I use a closed loop with one intake and two DIY eductors - I found that I got more thorough flow from that than my initial in-tank test of the same pump acting as a 'powerhead'.

(It's a dual submersible/external pump with a vortex impeller)

[gregg@AMS]

<a href=showthread.php?s=&postid=10505709#post10505709 target=_blank>Originally posted</a> by coralite
. Fast straight flow is more important than "random chaotic" flow.
i disagree with this statement. first of all, most cnidarians don't like straight laminar flow. they prefer pulsing flows. secondly, when you look at the physical dynamics of water flow, random, chaotic flow sends more "random" currents of water through the tank. laminar flow creates dead spots in areas outside of the path of the flow. if you have a circular tank with little in the way of structure to impede flow, then you can create a steady stream of current which will create it own momentum. but most people have some derivation of a rectangular tank with a lot of rock. at that point, straight laminar flow will create areas of heavy flow along with areas of little/no flow.

pulsing currents tend to break up as the water being pushed encounters the resitence of the static water. as it loses the force pushing it, it creates little vorticies which can swirl back ino the rocks, pulse on the corals a little (bring them food, remove waste, mucous etc.), and help keep some of the other junk in suspension. sure, you wll still get dead spots, but in my experience, these tend to be fewer and more concentrated.

the best method i have used on recirc. systems is to have a system like an acuated ball valve which runs off a programmable micro processor. the ball valve rotates, switching current from side to side, and creating more random flow patterns in the tank. its extremely effective (if a bit costly) and its the least strain on your recirc. pump (compared to turing the pump on and off constantly).

[coralite]

<a href=showthread.php?s=&postid=10506842#post10506842 target=_blank>Originally posted</a> by gregg@AMS
[B]i disagree with this statement. first of all, most cnidarians don't like straight laminar flow. they prefer pulsing flows.

Cnidarians don't care whether flow is laminar or turbulent, they just like it fast. For starters, it is almost impossible to produce actual laminar flow in anything but lab conditions. The reason I encourage people to produce "straight" flow is because this gets the water moving faster. The faster the water flow, the more turbulent it will be (on a small gas exchange scale) which will lead to higher rates of gas exchange. If you aim for "random, chaotic" your flow will be slower and it will have less turbulence which will lead to less gas exchange and lower rates of Photosynthesis and Respiration. Within the aquarium hobby there is some confusion as to what turbulence really is. This leads many people to misunderstand fluid dynamics in general.

for more information see the following articles.
Intro to gas exchange (http://www.advancedaquarist.com/2006/6/aafeature2)
basics of fluid dynamics (http://www.advancedaquarist.com/2006/11/aafeature)
Mass Water Movement Techniques (http://www.advancedaquarist.com/2007/1/aafeature)
Flow is more important than light (http://www.advancedaquarist.com/2006/9/aafeature2)

Jake Adams

[gregg@AMS]

so, all corals, anemones, jellies etc like fast flow? that's news to me.

edit:
ok, so i read your articles, and you have a lot of really good information in them. unfortunately, it is way generalized. i think some of your readers might get the impression that their Euphyllia is going to like the fast flow, so they're going to point a powerhead on it, and proceed to just shear the polyp right off the skeleton.

the reason that i say that they prefer pulses of water is because in an aquarium, it is the safest way to move water over your corals. i think if you can make a good surge device, that is probably the best way to go, as it incorporates the fast, chaotic flow that some corals like, but it also gives the corals a break from the flow.

[stevedola]

i dont think hes suggesting to point a powerhead directly at any coral.

I think his theory is to direct a power head in 1 direction and another in an opposite direction on a different plane allowing for an almost circlular motion. By not aiming the water sources directly at eachother it allows for less friction and fast currents which in end will reach farther and breakup against structures to create turbulance.

Not sure if I got it, I only read alittle of the articles.

[gregg@AMS]

<a href=showthread.php?s=&postid=10508069#post10508069 target=_blank>Originally posted</a> by stevedola
i dont think hes suggesting to point a powerhead directly at any coral.

I think his theory is to direct a power head in 1 direction and another in an opposite direction on a different plane allowing for an almost circlular motion. By not aiming the water sources directly at eachother it allows for less friction and fast currents which in end will reach farther and breakup against structures to create turbulance.

Not sure if I got it, I only read alittle of the articles.

that's what i took from it as well, but what i'm saying is that faster, more turbulent flow is not beneficial to all corals. many corals prefer light pulses of water, just enough to bring food/O2 and remove waste/CO2. many lagoon species (like a lot of the LPS corals) prefer much less turbulent flow than say, an acropora.

additionally, regardless of what type of coral you're talking about, and how much flow it prefers, they have all evolved in environments where they get periodic breaks from the flow.

[stevedola]

Well, youre right about differing flow requirements for corals. You cant blast a Euphyllia coral with the same amount of flow that you blast a Acropora coral with and expect to get the same extension as when the Euphyllia had a gentle flow. I think that flow should be a derivative of the corals you keep.

[RichConley]

<a href=showthread.php?s=&postid=10514453#post10514453 target=_blank>Originally posted</a> by gregg@AMS
that's what i took from it as well, but what i'm saying is that faster, more turbulent flow is not beneficial to all corals. many corals prefer light pulses of water, just enough to bring food/O2 and remove waste/CO2. many lagoon species (like a lot of the LPS corals) prefer much less turbulent flow than say, an acropora..


And the way you do that, is mass water movement, like hes suggesting. Getting mass water movement leads to great circulation, with none of the turbulence that makes euphyllia mad.

[ezrec]

At this point, I would like to bring up my 'Cactus Analogy':

Most novice reef tanks are as if a space alien wanted to make a garden. The alien say 'Hmm. These are all pretty plants, and they just need water occasionally, lots of light, and some air circulation.'

So the alien looks for pretty plants, that are reported to be 'very hardy'. And it picks a cactus, a pine tree seedling, some moss for ground cover, a rose bush, and some squirrels.

At first, everything looks great! Wonderful landscaping in the 10' cube, a layer of topsoil, and plenty of light. Toss in a few nuggets of 'Earth Critter Chow' every day for the squirrels, and all is well.

But the squirrels are unhappy, being nut feeders. After a week of near starvation, the squirrels finally start choking down the high-protein 'Earth Critter Chow', their metabolisms rebelling against it, and slowly causing kidney damage to the poor things.

But a month down the road, the moss is drying out, and the pine tree sapling is starting to wither. 'Hmm' says the alien, I should look on the GalaxyWeb. And sure enough: 'Earth plants like a lot of water'.

So the alien turns up the sprinkler, and sure enough, the moss comes back, and the pine tree is happy.

But a month later, the cactus begins to rot, and the rose bush is covered with mildew! And the squirrels are get very fat, but acting sickly. What to do! And the pine tree is already 10 ft tall, and about to outgrow the cube!


The moral of this story is that one organism's optimum conditions may be non-optimal, or even lethal to another. Reseach your critters, get them to the food, water (chemistry and flow!), and light *for their species*, and trade the one you can't support in your tank for the ones you can.

Everyone wants a Garden of Eden, with a little bit of everything colorful, but the real world doesn't work like that. A novice would have much better success tuning his tank for one specific reef geography (Fiji high-reef and Florida's Gulf of Mexico coastline reef seem popular in the states) and getting only organisms from that geography, than to go to the LFS and say 'I want that one - it's pretty!' and do their research when they get home.

Of course, you could always just have an aiptasia & hair algae tank.

[Aquarist007]

nice fable--Aesop--I enjoyed it :) plus very true for good coral husbandry

Due to the physical mechanicas and limitations of my tank and lighting systems I have tried to create zones on the reef.
My top layer of the reef is for placement of sps because of lighting requirements. This area gets the turbulent flow from two hydor koralinas at opposite ends of the tank. One is a three--two inches higher than the other ,a one, because in my middle area of the tank is a huge toad stool mushroom and other mushroom corals who don't prefer a strong current.
The lower zone in the tank has the flow from the two returns of the tank(by then the flow is alot weaker) plus lower light which I have found suitable for most lps corals.

[honda2sk]

lol that was awesome

<a href=showthread.php?s=&postid=10515288#post10515288 target=_blank>Originally posted</a> by ezrec
At this point, I would like to bring up my 'Cactus Analogy':

Most novice reef tanks are as if a space alien wanted to make a garden. The alien say 'Hmm. These are all pretty plants, and they just need water occasionally, lots of light, and some air circulation.'......

[miwoodar]

So...are we supposed to turn our tanks into whirlpools then?

Slower whirlpools for some tanks (as a generalization LPS) and faster whirlpools for other tanks (as a generalization SPS)?

What if nearly every coral in my tank (SPS) is getting between 6 to 10+ inch/second one moment and 1/2 inch/second the next moment? Should I switch to the whirlpool anyways?

[gregg@AMS]

<a href=showthread.php?s=&postid=10515288#post10515288 target=_blank>Originally posted</a> by ezrec
At this point, I would like to bring up my 'Cactus Analogy':
:thumbsup:

nail, meet hammer. that analogy is spot-on.

[miwoodar]

You mean, we're supposed to use our brains? What a concept!

Very nice fable by the way - I'm going to have to keep your username in the back of my brain so I can give proper credit when the time comes.

[Aquarist007]

<a href=showthread.php?s=&postid=10517618#post10517618 target=_blank>Originally posted</a> by miwoodar
So...are we supposed to turn our tanks into whirlpools then?

Slower whirlpools for some tanks (as a generalization LPS) and faster whirlpools for other tanks (as a generalization SPS)?

What if nearly every coral in my tank (SPS) is getting between 6 to 10+ inch/second one moment and 1/2 inch/second the next moment? Should I switch to the whirlpool anyways?

remember in my post above--you can create zones within the same tank and place the corals as to their flow needs.

[miwoodar]

Thanks - I was being a touch sarcastic (EDIT: regarding oversimplification). My tank suits my corals well.