Who rates skimmers

[Canadian]

Originally Posted by mr.wilson

A closed loop system offers the following benefits if executed properly...
1) Hidden influent and effluent lines.
2) Less heat transfer.
3) Less chance of stray electrical charge or shock hazard.
4) Less vibration.
5) No electrical cords in the water or running over the top of the tank.
6) Easy access to intake strainers.
7) More laminar and less turbulent flow for better inertia.
8) The ability to position flow anywhere in the tank.
9) Easy removal of pump if necessary.
10) True flow volume ratings.
11) High pressure flow.
12) Long pump life.
13) Only one cord to plug in.
14) Better circular flow.
15) The ability to locate the pump in a remote location (service area).

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.

[golf nut]

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.

This would make a great discussion.

[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.

[golf nut]

Originally Posted by sphelps

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.

That wasn't what I asked, so I will rephrase, if I throttle back a Dart to 3000 gph and make the outputs disperse similar to a tunze or vortech would they be similar?