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Syphon effect


Ducksta

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My Turn!

I think I have solved the mystery!

The problem of water flow is not hose diameter or length!

The problem of water flow is related to hose length but length is not the cause.

The cause is distance you are from the tank.

Yep!

You see.. Fish are curios things... every time I'm syphoning water I have to keep my fish away from the inlet hose in the tank!

Your problem of lower flow rate with a much longer hose might be that because you are too far from your tank (distance) you CANNOT see you poor fish getting stuck in the inlet of the syphon... all you are worried about it WHY I have poor flow...

Personally I think you take a head count of fish before and after syphoning.

Also look out for a fish with a BIG hickie the diameter of the hose!

hehe

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LOL Gigitt, not too sure about the hickies....but goldfish come out in pieces (only restricts the flow for a few seconds wink.gif ). Ever wondered how they make Telescope and other boggly-eyed goldies???? laugh.gif

merjo smile.gif

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cihlids_au is on the money with the Darcy equation. Now to modify it a bit and put some numbers in there. Assuming laminar flow:

user posted image

Looks tricky so far, but to get a ratio between velocity 1 (where h=1.2m and L=1.2m) and velocity 2 (h=4m and L=15m), like terms (diameter, denisty and viscosity) cancel out to give:

user posted image

Now if both were turbulent, friction factors would be about the same in each case, and the ratio between the 2 velocities would be closer to the square of the above, or around 1.9 times more water flow in the shorter pipe.

OK, think I have geeked up this thread sufficiently.....

rolleyes.gif

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rolleyes.gif Fish keeping aint "rocket science" otherwise most of us could be counted out! LOL.gif

But hey, 3 pages of this is pretty good going isn't it? tongue.gif

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Ok lets chuck in another variable....what about if there is water already lying in the hose, before you start to siphon wink.gif ....therefore having a break in the water column.............now we are looking at PE and KE ohmy.gif

merjo laugh.gif

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