Circulation Flow Patterns

[Hookup]

Well,
I'm not sure this is an "advanced topic" but what the hey...

I'm building my system, and installing the closed loop... which has me thinking about flow patterns, as I guess it rightly should.

What kinds of flow patterns do you think do the best job and why?

To narrow my specific question a bit, I'm referring to SPS dominated systems.

The way my brain works is flow is in one of 4 different patterns... everything else is just variations of combination of these patterns.

Rolling - The water is literally looping around your system, flowing away from the overflow across the bottom of the tank, and flowing back towards the overflow across the top of the water... like one big rolling loop.

random - A completely unpredictable and constantly changing pattern of water that flows differently all the time.

directed - Flow that is aimed specifically at corals/structure to create flow directly on the corals and live rock. Intensity is varied based upon the distance of the "flow device" to the "target location".

indirect - Flow that is aimed away from any specific coral/live rock that creates more "general" flow in the tank with nothing being specifically targeted.

What would the "ideal flow" be for a system that is mature with SPS, but still 'open concept'... so, do not think rock-wall pile, think open bonzi scaping...

Thanks for any input.
Tim

 

[Hookup]

Bump for opinions... (I feel like I've said something Taboo and everyone knows but me..)

 

[KarlBob]

I think the conventional wisdom calls for random circulation. People try to achieve this by aiming powerheads at each other, or by running wavemakers.

Recently I've seen a few people advocate rolling current. In addition to a vertical roll, you can also go horizontal: across the front of the tank in one direction, then across the back in the opposite direction.

There's another layer, too, between your directed and indirect categories. Maybe you could call it banked, or carom flow. Instead of aiming the powerhead directly at a coral, you aim it at the wall near that coral. The flow caroms off the wall toward the coral, becoming less laminar in the process.

Speaking of laminar, that's another discussion in itself. Some people like the laminar flow that comes from a closed-loop return, or a impeller-style powerhead like a Maxi-Jet. Others swear by the more turbulent flow of a propeller-style powerhead, like a Koralia. If you're interested in turbulent flow from a closed-loop, there are probably ways to achieve that, too.

 

[Hookup]

Well my intentions are focused around the design of my closed loop system for my 180g... which got put on hold because of this kind of discussion that came up with fellow reefers... (ARGH)

I thought my flow design encorporated a bunch of indirect and direct flow as well as two dedicated carom/banked flow outputs... but then the "barrel roll" people voiced up a concern... and the random flow people spoke... and then it got confusing... each has enough good ideas that I'm now completely confused...

ARGH!

 

[MrPike]

There's a 5 part study of waterflow here:

It covers quite a lot of the questions you just posed.

http://www.advancedaquarist.com/2006/6/aafeature2/view?searchterm=Flow

 

[Hookup]

Thank you for that link...

 

[KarlBob]

Thanks, MrPike. That was a fascinating article. Lots and lots of theory, with practical applications mostly in the last part.

Basically, the author seems to prefer what Hookup called rolling flow (the author calls it gyre flow), horizontal and/or vertical, with the current direction alternating at much longer intervals than most people seem to prefer.

I like the idea of longer flow intervals in each direction. Unfortunately, I use all propeller-type powerheads (AC Koralias and modified Maxi-Jets) that don't like frequent starts and stops. I'm afraid that even 15 minute intervals would quickly wear out this type of powerhead.

Maybe this would be a good application for the new DC Koralia powerheads. From pictures of the Koralia Wavemaker control panel, it looks like you could alternate the current at intervals from 2 minutes all the way up to 6 hours.

 

[Hookup]

I found the comments, though limited, about wave boxes interesting. It would seem that the author is not a fan and following his line of thinking, I can understand the potential issues that may in fact be problematic.

The article itself has given me a good idea for the flow I wish to achieve in my own design, which will use two closed loops systems, one to do mass water movement and a second one using an oceans motions 3-way to create random indirect flow.

I do wish the author would have discussed the role that flow plays in keeping detritus suspended as I think that a continual mass movement of water throughout the system will work well for corals, it might cause detritus to collect which could lead to issues if not removed.

Thanks for the thoughts.

 

[MrPike]

Here is a youtube example of a gyre using vortech pumps. I don't think its necessary to have the expensive vortech's to achieve this result though. You could probably use any of the koralia's, maxi-mods, or tunzes...

http://www.youtube.com/watch?v=Mz15R0gVMPA