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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.
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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
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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.
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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
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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.
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See above - not true.
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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.
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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.
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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.
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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.
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They also require regular cleaning that you don't need with closed loop systems.
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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.