[sphelps]

Vortecs have the advantage of the external motor which of course presents limitations however hobbyists have the choice to use them when appropriate and could also use Tunzes which solve many of these limitations.

1) Only suitable to be located at opposing ends of the tank. They cannot be located on the front, or easily on the back, or on the bottom, or within the reef structure, as closed loops can.

They can be located virtually anywhere, including within the reef structure. Maybe not as desirable in some locations but they also have the advantage of relocation if aquascaping or flow demands change, not as easy with closed loops. These pumps also have the advantage to pulse at critical frequencies to produce a natural wave type movement. Corals do not benefit from direct flow so I don't even see the advantage of pointing flow directly at the reef structure.

2) They are not directional, meaning they are limited to pointing forward (not up or down or at any other angle).

Tunzes are certainly directional, the new models have movement in almost all directions.
"they offer a lot of flexibility with respect to positioning and orientation of the water stream, which can be adjusted in such a way that an effective flow is produced over a long distance in the aquarium at lower power consumption."

3) They cannot be easily disguised inside or outside of the tank.

4) They require a network of wires running around the outside of the tank.

Cables can be tied back to one location like the back of the tank, or if all sides are viewable through the overflow.

5) They are slightly louder than a closed loop pump. CL pumps can be remote, while Vortechs must be on the side of the tank.

The further remote the more friction loss and most don't like to run large PVC pipe through their house. Vortecs are virtually silent if balanced correctly, and you can't even hear a Tunze running. CL pumps like a Dart are very noisy in comparison.

6) They give off more heat transfer directly to the tank wall (some acrylic tanks have had stress crack issues. According to Riddle, the external temperature is 138F.

Splitting hairs, heat will transfer from the motor to the water moving through an external pump in a similar fashion. The housings on the dart pumps I owned were warm to the touch and I've seen similar pumps fail when flow valves were shut and forgotten about. The pump is air cooled but still relies on the flowing water to remove part of the heat produced.

7) They cause vibration within the tank which can disturb livestock.

Interesting theory but I asked my fish this morning, they don't mind it. Pumps can also be turned down over night with controllers and create a more calming environment.

8) Circular or laminar flow is not possible with Vortechs. Water travels in one direction from end to end hitting the opposing wall or opposing flow. I read the velocity numbers, but I don't have pressure pump values to compare them with.

Turbulent flow could be a good thing as it would create a more random flow pattern adding to the snow globe effect. However you may have it backwards, a Tunze or Vortec spreads flow out over a larger area creating lower velocity which would promote a more laminar environment, closed loops often use jets which create high velocity patterns which disturb the water around it creating a turbulent boundary layer.

9) I don't know how often Vortechs need to be serviced, but CL pumps have at least 10 years before the volute needs to be looked at. Calcification only occurs on metallic pumps, so magnet coupled pressure pumps don't need to be soaked in acid. Vortechs have not been on the market long enough to establish longevity.

Completely false, external pumps, shaft driven, or magnetically driven, require frequent maintenance. Magnetically driven pumps require impeller and shaft cleaning as often as any power head. Shaft driven pumps also require frequent cleaning to prevent seal failure and build up which creates both resistance and noise. When I had issues with my reeflo dart the manufacturer stated the the impeller housing must be flushed and cleaned every three months to prevent seal failure. The seal also should be constantly checked for salt creep for the same reason.

10) There's always a #10. Vortechs are hard to use with tanks that have cabinetry that covers end walls or aquariums fit into walls where access is limited.

So a closed loop is easy to access with limited cabinetry access? I can't see how in most aquariums a closed loop offers easier access than power heads like tunze and vortec.


In my mind quality power heads like Tunze and Vortec offer the following advantages over CLs.

1) Easier setup and maintenance
2) Better resale and easier to incorporate in new tanks. Plumbing for a closed loop is expensive, I did a 4W OM on a clients tank and it cost around $400, very rarely can plumbing parts transfer to a new tank.
3) Can be relocated at anytime with minimal effort
4) Can be upgraded or down graded without major modifications to the tank
5) Use less power, greater efficiency a dart runs 22.5 GPH/W while a Tunze Stream 6000 runs 123.2 GPH/W
6) Create less noise, sorry but a tunze is quieter than a dart
7) Much better flow control and have better capability to produce more natural wave flow. The vast selection of electronic controllers is far superior to the OM and SCWD devices which are only ones I'm aware of.
8) Simplicity, closed loop systems require more experience in plumbing. You also can't really contain both a closed loop system and a sump system in one stand, it would have to oversized or very tight making maintenance a nightmare.
9) No tank modifications needed, Closed loops require a swiss cheese tank to hide the plumbing
10) Better reliability all the way round. The external plumbing required for a closed loop can be a dangerous game, bulkheads can leak down the road and replacement would be a tremendous headache requiring the complete dismantle of an established aquarium. People worry enough about the actual tank seams leaking, why add more potential for leaks?

I could go on but 10 seems to be the magic number.