Who rates skimmers

[hillegom]

Teeth not good? All the aquariums you buy with built in overflows that I have seen,have slots.

[golf nut]

Originally Posted by hillegom

Teeth not good? All the aquariums you buy with built in overflows that I have seen,have slots.

Yes they do.. why?

[mr.wilson]

Originally Posted by hillegom

Teeth not good? All the aquariums you buy with built in overflows that I have seen,have slots.

Teeth reduce the surface area by 50%, so a 12" overflow is really a 6" overflow. As water passes the teeth the surface tension is broken so you don't skim a quick, thin layer from the surface, but rather more water is drawn from below the surface.

Overflows that have a return line or other flow interfere with the surface tension (flow directed near, or away from the overflow) near the overflow cause it to draw water from lower down. You can do a flake food test on some overflows and see water (& flakes) pulled into the overflow box from straight down. Return lines from the sump should be located at the surface at one end with the overflow box in the opposing end or corner (depending on aesthetics). Centre overflow boxes are less efficient and promote dead spots. Water should flow straight across the surface mixing with old water and flow directly into the overflow box taking with it anything on the surface. This system discourages back siphoning with the sump return and provides superior surface swirl and subsequent ripples if you have metal halide lighting.

Tanks typically come with teeth because aquarium manufacturers don't like change. A single slot is cheaper, stronger and easier to build, but tank manufacturers are slow to change. Most of them still use wet/dry filters oversized drains (allowing air and flushing issues) and one pump systems. In the case of a coast to coast style overflow, teeth make even less sense because the water depth at the edge isn't deep enough to attract fish to swim over it.

[mr.wilson]

Originally Posted by Canadian

How about propeller pumps like Ecotech Vortechs or Tunze stream pumps? They address most of the cons of powerheads and consume significantly less power than a closed loop.

These pumps do solve most of the issues I mentioned, and they aren't a bad choice. Personally, I don't want to see any pumps or plumbing, but many people are concerned only about function and not about form.

They do use less power than any closed loop pump currently on the market, but the flow rates they have been designated are not the true values of the water they move. They also deliver volume and very little pressure. A pressure rated pump moves X amount of water plus all the other water it picks up and displaces as it travels across the tank. It's kind of a domino effect. If you were to add a dye to the effluent of the Vortech you would see less of it spread across the tank than what you would see with a typical closed loop pump.

Most of the closed loop effluents I use point up from the bottom to keep detritus suspended and to move dead water from lower regions to the air/water interface at the surface for gas exchange (oxygenation). Vortechs are only suitable for end to end flow, and they do it well.

Closed loop pumps draw in as much water as they put out. So do Vortechs, but the water intake doesn't have any impact on flow dynamics and flow is more turbulent (pumping into walls, rocks & opposing flow) than laminar (circular or rolling effect) without losing velocity due to friction or diffusion.

Typical powerhead set-ups direct water at the reef structure. This is not how it works on natural reefs. Water should change direction to offer suspended food from all angles. Good flow creates a snow globe effect. Chaotic flow with poorly placed powerheads drives detritus into reef structures and the sand bed.

A Sequence Dart pump uses 135 watts, and I pay $0.11 per Kw/h in Toronto including all of the extraneous charges. That comes to less than $11 per month if it runs 24hrs a day. If you can find a more efficient pump that truly moves the same amount of water (3600GPH) at half the wattage then you save $5.50 per month. A savings is a savings, but $5.00 isn't enough to tip the scale much.

I don't have much experience with prop powerheads like the Vortech but they look like they will claim the occasional invert or fish. They also require regular cleaning that you don't need with closed loop systems.

I find that drilling out rocks with a diamond bit or covering PVC ports with concrete or epoxy & aragonite makes them invisible in the tank. I'm trying to get away from swiss cheese tanks with multiple holes to keep costs and liability down. As long as you hide the pipes there's nothing wrong with running them over the top of the tank. You trim $1000 off of the cost of a big tank (no tempering or hole charges), production time is cut in half, and you save on bulkhead and valve costs. This brings the cost down to less than a comparable system with powerheads.

[Canadian]

Originally Posted by mr.wilson

They do use less power than any closed loop pump currently on the market, but the flow rates they have been designated are not the true values of the water they move.

Absolutely not true. In fact one of the pumps was recently scruitinized by Dana Riddle and found to move MORE water than the manufacturers claims:
http://www.advancedaquarist.com/2009/10/review

Most of the closed loop effluents I use point up from the bottom to keep detritus suspended and to move dead water from lower regions to the air/water interface at the surface for gas exchange (oxygenation). Vortechs are only suitable for end to end flow, and they do it well.

Again, not true. The pickup from my little Vortech MP20 draws detritus up from the bottom of the tank 14" beneath it to keep it suspended in the water column

Closed loop pumps draw in as much water as they put out. So do Vortechs, but the water intake doesn't have any impact on flow dynamics and flow is more turbulent (pumping into walls, rocks & opposing flow) than laminar (circular or rolling effect) without losing velocity due to friction or diffusion.

See above - not true.

Typical powerhead set-ups direct water at the reef structure. This is not how it works on natural reefs. Water should change direction to offer suspended food from all angles. Good flow creates a snow globe effect. Chaotic flow with poorly placed powerheads drives detritus into reef structures and the sand bed.

Strawman argument. Poorly directed and placed closed loop outlets do likewise. Your argument here is simply a function of poor application and has absolutely nothing to do with the inherent qualities of either a prop pump or closed loop.

A Sequence Dart pump uses 135 watts, and I pay $0.11 per Kw/h in Toronto including all of the extraneous charges. That comes to less than $11 per month if it runs 24hrs a day. If you can find a more efficient pump that truly moves the same amount of water (3600GPH) at half the wattage then you save $5.50 per month. A savings is a savings, but $5.00 isn't enough to tip the scale much.

And that 100+ watts difference in heat produced is pumped back into the room and eventually requires more hydro consumption in the form of increased work for the chiller, AC, fan to remove to keep temperatures down. Now you've probably doubled your savings to around $120 a year - I'll take that $120 in savings and go buy some pretty new frags.

They also require regular cleaning that you don't need with closed loop systems.

Just like you have to clean the impeller on a closed loop pump to remove eventual precipitation so too do you clean up the propeller on a prop pump - no difference in maintenance here.

[golf nut]

We are not really talking apples to apples here, both vortech and tunze claim flow numbers that becomes converted to gallons per hour of flow.
I would not argue their claims in the slightest, but just for a second could you answer me one simple question, if a vortech or tunze produce 3000- gph of flow , and you throttle back a dart to produce 3000 gph would the result be the same?

[sphelps]

Originally Posted by Mr OM

We are not really talking apples to apples here, both vortech and tunze claim flow numbers that becomes converted to gallons per hour of flow.
I would not argue their claims in the slightest, but just for a second could you answer me one simple question, if a vortech or tunze produce 3000- gph of flow , and you throttle back a dart to produce 3000 gph would the result be the same?

Tunzes and Vortecs push flow outwards in an expanding direction, this results in a larger area and therefore a lower velocity. Velocity is not that same as flow rate.

[littlesilvermax]

Originally Posted by Mr OM

We are not really talking apples to apples here, both vortech and tunze claim flow numbers that becomes converted to gallons per hour of flow.
I would not argue their claims in the slightest, but just for a second could you answer me one simple question, if a vortech or tunze produce 3000- gph of flow , and you throttle back a dart to produce 3000 gph would the result be the same?

I know what you are saying, and totally agree.

3000 gph from a dart will INDUCE a lot more flow then that in the tank. it is hard to compare that with a tunze or similar powerhead.

[mr.wilson]

Thanks for posting that article, Dana Riddle is an excellent source. It's good to see hard numbers and it's a shame that manufacturers won't spend the resources to achieve this themselves.

As I stated before, Vortechs work around most of the potential problems that arise from powerhead applications. I still argue that they have the following drawbacks...

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.
2) They are not directional, meaning they are limited to pointing forward (not up or down or at any other angle).
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.
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.
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.
7) They cause vibration within the tank which can disturb livestock.
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.
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.
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.

The extra 100 watts used by a closed loop pump (if that is truly the case) would not be 100% heat generation, and even if it was, it wouldn't impact the cooling system of a house. These days most people open windows before they turn on the A/C. I'm not about to argue that it contributes to heating your home in winter either

In my opinion, the flow from a closed loop pump has more flexibility to be used for better flow dynamics than a Vortech system. By no means does this make a closed loop system a license to use poor flow placement, nor does it exclude Vortechs from fulfilling some of the flow requirements of a tank.

If optimum flow dynamics are in place, which is more readily achievable with a closed loop system, a 15x turnover ratio can be just as effective as a 40x turnover ratio. It is arguable, that 3600 GPH with a closed loop is worth 4800 GPH from a well configured Vortech system.

If you aren't particular about aesthetics or flow dynamics, then Vortechs will work well for you. If you feel you can recoup the initial cost of a series of Vortechs with energy savings, then it has further added value.

[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.