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I'd like to apply physics principles to a home-experiment relating to my swimming pool.

The water should flow inner to 100 meters of black pipe and so it should become warm. Then it should return in the swimming pool.

But how can I carry the water from the swimming pool to the pipe? if I use a tight pipe, for the capillarity and putting the pipe vertically from the bottom of the swimming pool, the water should come up.. but it has to pass about 30 cm... is it possible to pass a similar hight using capillarity? (the pipe should be 30 cm over the water level) Which should the pipe diameter be?

If the idea is impracticable, which principle can I use?

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closed as off-topic by David Z Jul 25 '13 at 5:37

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I dont think capillary action is enough to circulate the water of the whole swimming pool. Maybe a siphon can help. – udiboy1209 Jul 23 '13 at 11:16
Why not connect the black pipe to your existing pump? – Kyle Kanos Jul 23 '13 at 13:38
look at a thermosiphon – mart Jul 24 '13 at 8:18
@mart what? ? – sunrise Jul 24 '13 at 14:22
@udiboy I'm studying your suggestion.. thanks! – sunrise Jul 24 '13 at 14:24

My understanding of capillary action is that it requires surface tension to move the liquids along. With both ends in the pool the surface tension cannot draw the water all the way through. A siphon would work to empty the pool but the force would balance out to zero when it re-entered the pool. Simple convection might work to circulate the hot water back into the pool, but it would likely be very slow. There is a percolating water heater design that circulates its own water supply. My suggestion would be to set up this type of system using the solar energy to heat AND circulate the water.

Ok. The basic idea is that when a fluid begins to move it has an effect on the whole body of fluid. So by applying a vacuum (or sucking) one end of the hose and keeping it below the level of the surface of the pool it will gravity flow over the wall of the pool. Essentially, the hose makes an upside down u with one end in the water and one end out of the water. The initial force comes from a pump (like your lungs). The continued kinetic energy is gravitational. As the water tries to reach an equilibrium so it will continue to run until the water outside is as high as the water inside the pool or the "inside" end of the pipe is exposed to air thus breaking the siphon. So the siphon will only fill the heating coil and the return line until the water level is equal to that of the pool, approximately 30cm short of the edge of the pool.

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As for passing 30 cm using capillary, this is possible. Using a nylon rope inside a pipe would easily accomplish this. – Diamondhills Jul 24 '13 at 3:50
Thanks for your answer. Could you explain me this step? "A siphon would work to empty the pool but the force would balance out to zero when it re-entered the pool."... which force? – sunrise Jul 24 '13 at 14:29

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