Poll: Laminar Flow vs. Turbulent Flow

[Shigshwa]

Used to have more turbulent flow with standard power heads creating random currents. Upgraded to a gyre and the tank literally woke up.

Basically this. I feel as though turbulent flow is good for complete coverage of equal flow on the coral flesh, but is harder to achieve sufficient volume of flow unless you run a bunch of PHs.

My two Gyres in LTC mode produce two gyre currents that rip like a whirlwind in my tank, but the alternation in strength helps to shift the point where they clash around the tank, creating turbulence around the tank while keeping the flow nice and high.

Since running these pumps, I swear that everything from my PE to my alk consumption have skyrocketed.

 

[Old Glory]

Good video from BRS showing the gyre and how to create it with different pumps.
https://www.bulkreefsupply.com/xf250-gyre-pump-with-controller-5300-gph-maxspect.html

The video shows a top to bottom flow pattern. The pump is placed high and causing the water to shoot across the top of the tank and return across the bottom...I'll call it horizontal flow. I think I read somewhere that creating whirlpool flow is desirable. In essence its the same type of flow as a horizontal gyre just on a different plane...across the front and back rather than the top and bottom. Any thoughts?

 

[stevieduk]

80 gallon shallow with 2xgyre (150 and 250 on 250 controller at 70%max random flow) and 2 jabeo wp-25 on S1-else.
Pretty random and turbulent I’d say.

whats a gyre pump

 

[lou dog420]

I guess I would say mine is turbulent. I run 2 mp40s on a 4 foot tank directly across from each other. One runs 75% constant while the other runs 75% reefcrest, and they alternate every hour. Seems to work well for me.

 

[ReeferMaddness843]

whats a gyre pump

http://www.maxspect.com/index.php?option=com_content&view=article&id=87&lang=en

 

[mcarroll]

I was just going to say the complete opposite lol, that the ocean currents usually provide laminar flow. I'm now curious if I'm missing something. What makes you say random turbulent flow?

+1

Tides cause the most universal currents – laminar.

Ocean currents –laminar – are probably limited to fore reef/drop off environments but are similarly consistent.

Breaking waves/surge – turbulence – is generally limited to exposed surface environments.

Tunze has a great video on their YouTube channel explaining flow vs. turbulence. (I’ll post it later if nobody else does. Not near a computer.)

 

[sfin52]

@saltyfilmfolks thats a great read. I just skimmed it. I’ll have to dive in deeper, later this evening. Why do I think you suggested this poll.

 

[saltyfilmfolks]

@saltyfilmfolks thats a great read. I just skimmed it. I’ll have to dive in deeper, later this evening. Why do I think you suggested this poll.

Hahaha. I honestly did not.
But I do love flow and the study of it. It was a huge Hang up for me starting out too.

And my secret dream tank is a true gyre tank. I have a passion for seafans and gorginia.
My quest is for the BlueBerry Gorgonian.

 

[sfin52]

I was sold a gorgonian when I first start it was gorgeous. too bad it was way out of my league to care for it. I hope you get to that point.

 

[saltyfilmfolks]

I was sold a gorgonian when I first start it was gorgeous. too bad it was way out of my league to care for it. I hope you get to that point.

Yup. Two years of that trying to figure it out. I was off gorg buying and and more research for probably five or six , actually until recently, and got some easy ones.

 

[mcarroll]

 

[jason.kennedy.98478]

We often talk about lighting in aquaria - this light or light type vs. another. But the concept of flow isn't discussed as often with the exception of "What's the Best Power Head?". So let's talk about water flow. I'm by no means an expert but it can be argued that water flow is at least as important as lighting to the health of our corals.

So I'm curious how your current water flow pattern is set up now. Is it more of a laminar flow or do you have it designed to try to get a turbulent flow? Many things play in to this like the size of the aquarium, the nature of the rock work and coral placement, and obviously the quantity, power and types of flow generators (power heads, gyres, etc) you use. So let's start with where we are now and maybe through this discussion, we'll learn what we "should" be looking for.

Let's discuss.

So do you have a reynolds equation that is relevant to a fish tank or are we talking opinion based laminar vs turbulent flow

 

[mcarroll]

So do you have a reynolds equation...

Do you really want a reynolds equation???

Oceanic Forcing of Coral Reefs has some pretty interesting information that addresses this – might be more interesting than a reynolds equation!

On of two sports intersections with reefs.....this one related to baseball (most ball-sports, really). They care a lot about reynolds equations. I know "Oceanic Forcing..." does not suggest a sports intersection, so trust me and read it!

(The other intersection I know is drag racing! Them guys know pumps!! ;Nailbiting;Jawdrop Fuel pumps that get around 100 gpm. Yes that's an "m" not an "h". Aka 6,000 gph in a fuel pump. Yessssss. ;Stig)

 

[mcarroll]

Ask this guy about reynold numbers (start at 0:50 if link doesn't take you there) he's in between two 8000hp dragsters at the start line (the cars barely appear in the vid):

(I know there's no seawater, but this vid is actually a really great – if physically and emotionally stunning – example of reynolds in action. As mentioned in the article.)

 

[littleruttiger]

There is no such thing as a Reynolds equation, beyond the expression that defines it.
The Reynolds number arises from non-dimensionalizing the Navier-Stokes equations, which are a system of partial differential equations that model the velocity field of a fluid. It has some physical interpretations, some of which are very loose.
Turbulence is a physical phenomenon characterized by rapidly fluctuating, random (or, random appearing) velocities, the appearance of vortices, etc.
Turbulence is often associated with a high Reynolds number, but not always. For instance, any flow with a large characteristic length will typically have a high Reynolds number, but need not be turbulent.
I would imagine that, as far as aquarium flow, we would want the water to be well mixed, and with a relatively high velocity near the corals to bring nutrients to the corals and carry waste away - ie we want a certain number of the fluid particles, and what they carry, to impact a square inch of coral tissue at a certain rate.
A truly turbulent flow should always do that (as far as I understand, which may not be saying much), but I don't know that a power head or two set on random pulses actually produces a turbulent flow, or, more accurately, a turbulent flow throughout the tank. So I don't know if turbulent flow is the correct descriptor in the poll question. A laminar flow need not do it either (a gyre in a tank with no rocks will have low flow spots in the middle and corners).
Growth pattern considerations aside, a more random flow vs a more laminar flow I'd guess to be a toss up, as long as they accomplish what the "point" of high flow is.

 

[Neptune1707]

I currently have a problem with a couple of my leathers in my home tank (Red Sea Max500). It’s about the same time that my Maxspect gyre 150 started failing. It’s limping along now till I get new gyre In a couple weeks. Getting the new 250 and one for each end. Think my colt coral like the flow and now not getting it. Retracted for about 2 months. Not dying but not happy either. On my office tank and my bosses tank I’m running 1 mp10 in each 30 gal tank. Leathers in those tanks are so fat and happy. All tanks use radion lighting with roughly same settings. All water params are in check...so it’s been my experience flow is one of those parameters that may get overlooked, but essential for Cora health. I’d say the variety of the flow is unique to each tank depending on scape, coral type and space between coral and pump flow. Just have to experiment till you see your corals extend to their max, then they are happy! Adjust flow accordingly as they grow. Just my 2 sense worth

 

[sullyman]

In my reef tank it was about random turbulent water. I'd show it but have to find new photo sharing site.
It was a 193g 53"x32"x24". The over flow was 32" as it was a peninsula set up, return was a reeflo barracuda feeding 5 3/4" returns.
I had 2 turbelle streams mounted to wavy sea ocilators, one stream was a 6100 the other was a 6200, I also had a 6100 in a tunze rock aimed at the front about 16" back from it. That tank can be found if you care to look, google "sullyman sps tank", most places lost the pics thanks to the Bucket too but Chicago reefs still has the pics. You can find 5 month pics, 1st year pics, 2 year pics. You'll see great growth rates and full grown colonies. Lighting was T5's that the mainly Acro tank loved. Ran a Calcium reactor and had a great skimmer.
One of the many things I observed was that the coral grew toward flow and light but mainly Flow.

 

[Devaji]

so did we ever come up with an answer to this age old question?
wondering what is best for a LPS dominate mixed reef?

 

[saltyfilmfolks]

so did we ever come up with an answer to this age old question?
wondering what is best for a LPS dominate mixed reef?

Anecdotal, but in my reefs , both work.

 

[mcarroll]

Like the vid in post #51 points out, flow from propeller pumps is inherently turbulent, so there's no "either/or". In most tanks it's "both". In better tanks, there's A LOT of both.