If you could - re: circulation

[Parker]

I'm going with closed loops with my new tank. One closed loop through the bottom of the tank and one over the top. I'll most likely have an Ocean Motions 4-Way on one of the closed loops. I prefer the clean look without seeing equipment.

[mark]

If doing a CL, can design so returns aren't noticable (see OM picture forum), something a little harder with PH unless using something like a Tunze rock.

PH and CL can both also give noise. Might get a overall higher flow with PHs than a external pump for the same noise level if not running a separate fish room (do find my Dart though ok for being under the tank).

My tanks been up for a couple years with a CL and still no regrets.

[sphelps]

Both can be good, in general for larger tanks a closed loop can be a cheaper alternative. Here's one I did on a custom 270 gallon:





Pump outputs were placed through the bottom pane and the inputs on the back to avoid sucking in sand. Also I went with two inputs rather than one single to reduce the suction velocity.
I also installed a 4-Way OM and mounted it sideways over the sump for easy maintenance which is key for such a system, you need lots of space otherwise it's just a headache waiting to happen.



The outputs where covered with rock using some zip-ties .






So you do get a clean look with the closed loop, but it will probably use more power than a tunze setup. However a tunze setup is going to cost a little more but if you plan ahead you can generate a clean look this these powerheads as well. I've always liked the idea of making your tank a little wider and building an acrylic curtain in the back and placing the tunzes behind the curtain alowing only the nozzles to penetrate into the visible tank area through strategically placed holes.

A tunze setup will also give you more control and better alternating flow. In my tank I use both, a closed loop to produce the majority of the flow rate and a tunze to provide a short right angled wave and better water alteration.

[levi1803]

WOW, awesome looking setup

[Delphinus]

Are closed loops *really* a cheap alternative? Seems to me when you start getting into the >2000gph range, the DC drive motors (Tunze, Korallia, Vortech, etc. etc. e-i-e-i-o) edge out the inline pumps...

[fkshiu]

One thing about closed-loops that is easy to forget is the cost and complexity of all the extra PVC. All those unions/valves/elbows/etc. can really add up in a significant way.

[sphelps]

Well, I look at it as a cheaper option. To me I see a closed loop using a Dart pump and 4-Way OM costing around $600-700 plus you have to consider plumbing and drilling costs which can make a total around $1000.
You can get a tunze kit with 2 pumps and controller for the same price but the 4 way OM provides 4 points of flow origin where as the tunze kit only 2. So really you need two tunze kits which costs double. So closed loops are GENERALLY cheaper for larger tanks.

Although some would argue you get way more flow from all those tunzes, try running a Dart at zero head next to a tunze and tell me which is greater. In addition the fact that you can use nozzles on a closed loop also creates high velocity streams which travel further and you with multiple nozzles pointed at multiple areas of the tank you eliminate more dead space.