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tank with no electric power.

Started by Guest_Zephead4747_* , Jan 13 2008 08:05 PM

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42 replies to this topic

#1 Guest_Zephead4747_*

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Posted 13 January 2008 - 08:05 PM

with the gravel vacs, if you start them by shaking them, will they siphon continuously if there is water to siphon? I kind of have an idea for a filter using these things if they do.

I may have more questions later, but for now anyone with ideas/answers is welcome to post.

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#2 Guest_hmt321_*

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Posted 13 January 2008 - 08:10 PM

once siphon is broken, no water will flow

edit, sorry misread post, siphon will continue as long as there is water, the out flow is lower than the inflow, and the siphon is unbroken (no air gets in the tube)

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#3 Guest_Skipjack_*

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Posted 13 January 2008 - 08:30 PM

Great Idea, but people have been working with perpetual motion for centuries. There is no free lunch. You can siphon the water to a lower level, but you cannot bring it back up without a power source.

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#4 Guest_viridari_*

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Posted 13 January 2008 - 09:16 PM

Great Idea, but people have been working with perpetual motion for centuries. There is no free lunch. You can siphon the water to a lower level, but you cannot bring it back up without a power source.

Wellllllll that is not 100% true.

You can get some of the water to go back up hill, but not all of it.

http://en.wikipedia....i/Hydraulic_ram

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#5 Guest_edbihary_*

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Posted 14 January 2008 - 01:36 AM

You can get some of the water to go back up hill, but not all of it.

But of course, if it all doesn't go back uphill, his tank will eventually be empty. Which brings you back to the truth of what Skipjack says. No filter can be run without some sort of external source of power.

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#6 Guest_Zephead4747_*

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Posted 14 January 2008 - 06:59 PM

my idea was having one of the sides of the tank to have a hole in it, and then to have a piece attached to it that goes up, leaving an opening. The siphone would siphon water to a bucket which would have media in it and holes in the bottom, then go from the tube to the bucket and pour back into the tank.

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#7 Guest_Newt_*

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Posted 14 January 2008 - 07:24 PM

my idea was having one of the sides of the tank to have a hole in it, and then to have a piece attached to it that goes up, leaving an opening. The siphone would siphon water to a bucket which would have media in it and holes in the bottom, then go from the tube to the bucket and pour back into the tank.

Like Skipjack said, the water will not flow continuously without something pushing it, i.e. a pump.

I'm not sure I understand your design, but the laws of physics simply will not allow such a design to work. If the bucket is situated lower than your tank, then the siphon out of the tank will work fine but the return flow will not: you'll just be filling the bucket until the water level in your tank drops below the hole, then flow will cease. If the bucket is situated higher than the tank, you'll have the opposite problem: the return flow will work, but the siphon will not. If the two are at the same level, you will have no flow at all.

So, you're just going to have to get a pump, or else figure out what to put in a tank with no filtration. Now, your design will work if you are the pump. Start with the bucket below the tank; let the water flow into the bucket. Then set the bucket up on a shelf or something that's higher than the tank and let the water flow back into the tank. This will be time intensive, and it will mean that the water level in your tank will fluctuate a lot, but it won't use any electricity.

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#8 Guest_arnoldi_*

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Posted 15 January 2008 - 03:38 PM

Archimedes screw powered by gerbils on wheels, thats the ticket.

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#9 Guest_Newt_*

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Posted 15 January 2008 - 03:47 PM

Now you're talking! You'd have to upgrade to Guinea pigs for bigger tanks, though.

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#10 Guest_andyavram_*

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Posted 15 January 2008 - 04:34 PM

What about a continuous, energy free current without a filter? Could you take a regular siphon, have the inflow near the top of the aquarium, loop it out of the tank and put the outflow at the bottom and have a current without any pump to move the water?

Andy

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#11 Guest_Newt_*

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Posted 15 January 2008 - 04:44 PM

No, the water will simply sit in the siphon. No energy=no flow. There will be some exchange of water between the tank and siphon, but not a net flow; it would be just the same as the exchange of water between one part of the tank and another part of the tank.
Flow in natural systems is always energy dependent: Streams are forced to flow by gravity and are replenished by the rain cycle, which is driven by heat (mainly from sunlight). Tidal flow is driven by gravity, just like a siphon, but the gravitational force shifts (due to the revolution of the moon around the earth); otherwise the water would quickly find its stable position and stay there, which is the same thing that would happen in your continuous-siphon idea.

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#12 Guest_truf_*

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Posted 15 January 2008 - 04:45 PM

What about a continuous, energy free current without a filter? Could you take a regular siphon, have the inflow near the top of the aquarium, loop it out of the tank and put the outflow at the bottom and have a current without any pump to move the water?

Andy

No, you can neither grab both of your elbows with one hand, nor grab one of your elbows with both hands.

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#13 Guest_andyavram_*

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Posted 15 January 2008 - 05:09 PM

So why does a siphon work when you change water in your aquarium? It is flowing, quite readily without any engery input so to speak. I see this as more or less the same thing. As long as the intake opening is above the output opening and the hose loops higher than the water level.

I have been meaning to test this theory but just haven't gotton a gravel cleaning hose yet, although I figure if it would work people would have already incorporated it into a tank somewhere.

Andy

BTW, I have a third hand so I can grab two elbows with one hand. It was hard playing patty-cake as a child.

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#14 Guest_Newt_*

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Posted 15 January 2008 - 05:30 PM

A siphon only works when the output end is lower than the water level in the container in which the input end lies. Lift the output opening to the same level as the water level, as in your scenario, and flow stops. Lift it higher, and flow reverses- the water in the siphon flows back into the tank. Get yourself a length of hose and a couple of buckets and play around with them outside- you'll figure it out soon enough.

The energy input when you siphon your tank is the potential energy differential between the position of your tank and some lower position where you put the siphon output. It's just like when you climb to the top of a slide- you've increased your potential energy, and can convert it into kinetic energy by sliding down the slide, but you can't slide back up- you have to input more energy by climbing back up.

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#15 Guest_ashtonmj_*

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Posted 15 January 2008 - 08:44 PM

There isn't anything really to further debate. It boils down to simple physics.

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#16 Guest_edbihary_*

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Posted 16 January 2008 - 01:13 AM

There isn't anything really to further debate. It boils down to simple physics.

True. And Newt has done well as a physics teacher.

The total energy in the system, in the field of hydraulics, is known as head. There are three components of head. There is potential (or elevation) head, pressure head, and velocity head. Apart from losses due to friction, the sum of these in the system is constant. The siphon converts head from one form to another. The difference in potential heads drives flow. This is the elevation of the water surface in your tank minus the elevation of the water surface in the receiving container. Typically you are siphoning into a bucket, with the outlet end of your siphon submerged in the bucket. As the water level in the bucket increases, and the water level in your tank decreases, the difference in potential head decreases, and the flow rate slows. When the elevations are the same, the flow stops; there is no head difference to drive the flow. If the outlet water level remains lower than the tank, the tank will completely drain. The potential head from the tank will be converted into velocity head as the water continues to flow, and/or, there will be head losses due to friction in the siphon tube and turbulence in the outlet receptacle. These head losses are converted to heat, and cannot be recovered by the system. The losses due to friction are the reason you cannot have a perpetual motion machine. You must always add energy to the system to overcome the losses.

To put it more simply, water always flow downhill.

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#17 Guest_MScooter_*

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Posted 16 January 2008 - 03:25 AM

the idea of this thread could be considered as entropy

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#18 Guest_hmt321_*

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Posted 16 January 2008 - 07:15 AM

the only possible way to make a viable aquarium system not dependent on electrical power is to continually feed fresh water into the tank and allow waste to leave via an over flow, where I live (The City of Mobile, In the Great State of Alabama) water will run you 0.019395 cents per gal, so if you were to replace the total volume of a 55 gal tank every day it would cost you $388.29 per year (that does not include the cost of de-chlorinating the water, I estimate that to be about $35.00 per month, running 2 charcoal filters in tandem)

so for a year its $808.29 (after your initial start up cost of course)