Water flow better as a vortex vs random flow

[FunkieReefJunkie]

I remember reading the advanced aquarist article. It sounds great in theory, but as pointed out the energy gets wasted bouncing off walls and corals. But what if you took a closed loop system with say every output facing right all the way round ? The flow would be self correcting maybe? You could take it a step further and angle them slightly downward forcing flow top to bottom? But it seems to me if I wanted to take this to the 'enth degree I'd go cylindrical with one kick arse tunze. :lol: The question is would the fish look like they're swimming against a washing machine spin cycle?

 

[WarrenG]

The energy of water bouncing off walls and corals isn't wasted because the bouncing creates useful turbulence. I think the currents need to flow in both directions-one at a time, not always the same direction. A 2-part closed loop?

 

[aninjaatemyshoe]

One of the problems with a "vortex" flow scheme is that inevitably you have a center where there is next to no water flow. As you go away from the center, the flow velocity increases proportional to the square of the distance. This means that you will essentially have a center zone of very little flow and an outer zone of much higher flow. The effect of this is to drag all debris towards the center of the vortex. So, you'll get crap accumulating in the middle of your tank. Depending upon your maintenance scheme and how you aquascape, this could be an issue. This really is more of an issue if you are talking about circular water flow with respect to the horizontal plane. A better scheme would be to have the vortex with respect to the vertical plane. This way the tendency for debris to accumulate in the center is counterbalanced by gravity pulling it towards the bottom of the tank.

 

[WarrenG]

The rocks interrupt the flows. The widths of the flows are plenty wide enough in my tank that is near 30" deep (front to back).

I use two power heads pointed towards the front of the tank to periodically interrupt the "perfect" flow circulating around the exterior of the tank.

I think a key is to use your pumps to get the water flowing for at least few minutes mainly in one direction (left to right, and vice versa) and give the flow somewhere to go once it gets to the other end of the tank. This could be further back or forward, or up or down.

A nice thing about a flow that goes around horizontally is that the water movers can be in the back center of the tank, even hidden by rocks or something else, not on the sides of the tank.

 

[reefworldaq]

I think The best is random flow. If you can use wavy-sea product and combine with tunze or eductor.

 

[EnderG60]

I like how everyone fights the obvious answer....BOTH

I will be running a CL with many eductors to swirl the tank at timmed intervels. Then the return pump will be on a OM also with eductors, and some tunze's on a sea swirl for random flow. Oh and the wave box Should be enough flow for a 180, and hideable with some creative rock work.

 

[miwoodar]

^^^ You had better duck and cover for that!:lol: :lol:

I've seen this topic pop up a few times in the last year or so. I like my random flow and see good growth in my corals so I'm not likely to change it any time soon. When a few well respected authors start jumping on the gyre bandwagon, I might give it a little more consideration. As of now, I've only seen one author give it direct support (correct me if you know of anyone else). I'm not really one to 'go with the flow' but it does seem that the majority of the authors this hobby looks up to still preach random, turbulant currents.

 

[WarrenG]

I don't think anyone is saying that an all-random flow isn't good. The difficulty with all-random is that getting proper flow with a random method requires more equipment than using flow that's more like currents.

For example, with a flow more like currents you can achieve 10-15cm/s flow in a 4' long tank using a sump return pump with just enough flow-through to cover your skimmer, heater, refugium, etc. and some movement with the outlet, along with 2-4 modded MJ's or similar.

 

[a1amap]

The main reason I bring this up is I am upgrading from a 75g to a 210g and my main goal is to not have a larger inpact in the co2 being released from power consumption. We all talk about saving a reef but rearly do people actually try to do something, no matter how small.
If the flow traveled the same direction I could see it effecting the growth pattern of the corals. If you altered the flow direction every so often this would correct some of the negatives of going in a whirlpool. I agree, as the water bounces off objects whether coral, rock or the walls of the tank it will create turbolence. But that would be a good thing. As for losses because of the bouncing, I think the cohesive nature of water will pull the water around the tank from top to bottom and after the rockwork and corals created the turbolence it would be pulled into the whirlpool again. A maxi jet w/mod placed in the rock work to give more flow to select corals and could be hidden in the rock work. The rock for the new tank will be mostly concrete and will incorporate the plumbing.

If this idea works it will save me a lot of watts to be converted to extra lights. I will convert my lights that are vho to t5 and keep the 2 mh lights. They will be located in the center so my sps corals will be located there with softies around the sides.

 

[aninjaatemyshoe]

"Random" flow is generally a good thing, but it depends upon what you are talking about. Traditionally, it has meant placing a bunch of powerheads in the tank pointing every which way and possibly having them on some sort of wave timer. This is a very inefficient way to move water in your tank, and certainly rather unnatural. The water will be tussled around creating areas of high movement right next to areas of very low movement. This creates ripping shear forces that can stress or even damage certain corals. With such a flow scheme, you have to be very careful about coral placement; to find a spot with just enough flow without high shear forces. Now, there are much better ways to produce random flow. The Waveseas and Sea-Swirls are quite a bit better than the old powerheads placed every which way method. IMO, the best method is a surge device.

Gyres aren't the only way to produce uni-directional laminar flow. Using a closed-loop that pushes water from one side of the tank and pulls it from the other also accomplishes this, as does the "vortex" method. The idea is that it yields a whole lot more bulk movement of water than random turbulent flow. One thing to get straight is that turbulence is not the same thing as randomness. Turbulence is the state where the water flow pattern is unstable and chaotic, as opposed to smooth linear laminar flow. When you have a general laminar flow in your tank, the water bouncing off the rocks, corals, walls, and substrate will create local areas of turbulence. Turbulence is quite beneficial for diffusion and mixing, ie it helps corals breathe and expel waste. However, it is very inefficient in terms of overall bulk motion.

In the end, it is best to have a combination of uni-directional laminar flow punctuated with intermittent periods of highly turbulent flow.

 

[a1amap]

Just curious, but would it be possible to create a vortex on the outside perimeter of the tank and a reverse vortex on the inner area of the tank? I figure since I am making the rock I could create 2 islands where the inner flow could bounce around on. Where the water currents mixed along the long side of the tank there would be turbulence. Would this work and would you be able to use a lesser pump and receive the benefit of laminar flow (little pump, large flow) while creating some random and turbulent flow? The biggest hurdle will be keeping the inner vortex separate enough to create a whirlpool.

 

[reefnewbie54321]

Undirectional laminer flow is the best possible option for your tank and still many people have yet to realize it. The undrirectional laminer flow hits the corals and rocks and creates turbulent flow by the jeddys that form around coral branches and rocks structures.

The whole whirlpool tank is actually called a gyre or mass water movement. There is a whole 5 part article on advancedaquarists about water flow. Those interested in providing the best possible scenario for there tank should read it.

Here is a link to part 5 that discusses gyre tanks and mass water movement,

http://www.advancedaquarist.com/2007/1/aafeature

 

[a1amap]

Thats a great article. Whats really sad is LY I bookmarked that article to read later and never went back to it.

 

[linyreefer]

Go with a Vortech or pair of them 500-3000 gph.

 

[Telford]

whirlpool flow

whirlpool flow

I own a 80g Tenecor cylinder tank with center overflow. I just talked to the guy that designs/manufactures the tanks about an unrelated question and i asked him about water flow in the tank. He actually suggested pointing the two power heads in the same direction, creating a whirlpool.

I haven't done it yet but i think i'm gonna try it and see how it works, looks and the reaction of the inhabitants!

ps. if anyone has a cylinder tank i'd love to chat with them to ask a few questions.

 

[a1amap]

Seems very possible to reduce the pump power without sacrificing flow. If I can reduce my 2 x 150 watt pumps down to 150 watts creating a gyre I will plumb the other pump to go in the reverse direction on a timed interval. I also plan on running my skimmer at regular intervals.
I figure the pumps will switch every 6 hours and stay on for 6 hours. A half hour before the switch of the gyre the skimmer will turn on and stay on for 1.5 hours. for a total of running for 8 hours per day. I think as the gyre changes direction, in that chaotic time before the next gyre forms all the excess food and nutrients will be in suspension. Also food will not be wasted in the skimmer. Since my skimmer rarely seems to pull nutrients out of the water except during feeding time, I think it will be more effective. I have been running skimmerless for 3 weeks as a test of the biological filtration of the tank. I am using almost nothing, no skimmer, no floss, only a foam cover on the return pump to keep snails and shrimp out. I wash the cover out once a week. There has been no increase in the nuisance algaes or any cyano. Seems to be holding it own. I have continued the regular water changes of 10% every other week(about 10 gallons)

 

[Zach_Attack_82]

So I just read through this thread and a couple things come to mind. First I have spend time in the ocean and have seen both types of flow in action and i believe they both have their place. I've spend time in shallow reefs, one minute your being pulled out to see the next back, after that up the reef then back down and every combination in between. On the other hand I have hit sections where every time I had been there same current flow. My personal opinion, most shallow water reefs have a prodominately random surging, wavy, flow, but there always is the exception. So I prefer to create a very quick changing random flow in my tanks. I have a 75g reef tank that has 4 randomly alternating flows, with two flowing at a time, every 5-7 seconds the flows change. To achieve this i used a 1500gph pump with a head height of 32ft, needless to say this moves alot of water. This set-up is relatively new so any thing can happen.
Now in defense of the whirlpool theory, I have seen this used with much success for years.......but never in a reef tank. I have seen countless shark systems that thrived for many many years using this technique. These are just my opinions and enjoy hear everyones pros and cons discussions, keep em coming.