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SinCrisis 12-29-2010 04:28 PM

using bubbles to push water?
Hey all, this isnt exactly a DIY project but a concept question.

How much water pushing power can be expected from air pumps? In the last contest green wiki uses air to pump water through his bamboo stalks and whisper has internal filters that use air to push water through filtermedia. My question is, how high can air be expected to push this water and how can that rate be controlled, ie increased height, flow, etc. I am wondering if the air can push water high above the waterline (yes its a waterfall related question but not for my DIY project) or if the water will just end up going around the bubbles and fall back down to the waterline.

Im not sure if this is the correct way to illustrate my question, does anyone understand what im asking?

RandyTX 12-29-2010 04:36 PM

I fully understand.. and am a retired machine design engineer. You can raise the water a fair amount. Try a control test. Use plastic tubing and try just an open end of the air supply tube so that the bubbles are about the size that fill the diameter of the lift tube. Do not run the supply tube down the lift tube so the lift tube will diameter won't have any odd shape inside. Instead just insert it up some from the bottom. If you can get the bubbles to stage water, bubble, water, bubble, etc, etc, you may be surprised. To get more lift try lifting to a small "tank" with enough depth to set-up a second stage, etc. Be sure any stage lift tanks are designed to overflow back to the main tank.

Let us know how it goes.

SinCrisis 12-29-2010 08:28 PM

SO this would only work with large bubbles filling the size of the cylinder? if it was a rectangular tunnel it would not work? Also can it be done with a small reservoir at the top? so the water doesnt come out in spurts but as a flow?

RandyTX 12-29-2010 10:59 PM

Not exactly so limited. You can use bubbles out of a stone.. But I found more lift done by bubbles about 3/6" inside a tube of that size. As far as a buffer tank at the top, a simple pool at the falls will do fine. You can test all this with plastic tube and a drinking glass leaning some so it spills out like a water fall. Then you can determine what works best with experimentation.

What I used was a U shaped tube at the top with a hole at the top and a short tube sticking up to let the air out at the top so water could then run into the resivor. For more volume of flow use more lift tubes.

bearwithfish 12-30-2010 07:02 AM

hmmm i would argue that from my experience i got way more lift from more rapid smaller bubbles .... for example when building various filters i got better resaults with a small ceramic stone versus open ended or even the larger blue stones.... the main thing to consider however is the rate of the bubbles when using an air pump with two ports i found plumbing them together worked far better... jut my 2 cents....

SinCrisis 12-30-2010 08:37 AM

@Randy and Bear,

Do you guys know this works? I always thought the bubbles would have to fill the tube to prevent the water from sliding around the bubble, but it seems that most any size bubble will create lift?

I am starting a new project (i need a break from my other project since its really frustrating and i need to step away from it for a little bit) and one of the goals is to create a micro wet/dry that uses an overflow to pull water and air to push water back, but im having trouble conceptualizing what kind of mechanism i need to make the return flow fast enough to make it effective. Air is my only current option since I do not have enough space for a pump of any kind, the space i have for this filter is only 4x4x8 inches and it needs to be easily cleaned, only planning to use foam/floss and a heater.

Any ideas on how to calculate the rate of flow with bubbles and what kind of flow would be optimal?

bearwithfish 12-30-2010 08:43 AM

here are a few examples of air lift type filters and water movement

these will give you some idea on the movement part and then you tweek and apply it to your concept///

RandyTX 01-01-2011 04:14 PM

Yes, it works, I have done it much in the past. Though currently I am attempting to use as little air as possible in my systems.

SinCrisis 01-01-2011 06:29 PM

Oh typo, i meant to ask do you know HOW it works, it seems in my haste i omitted the most important word in the question...

RandyTX 01-01-2011 09:25 PM

Simple physics. The air bubbles rise and in the process trap, draft, and adhear to water on their way up. This causes a flow of water up the tube. Then centrifugal force plus the additional water rising with the bubbles from below force the water to climb the tube higher than the water level in the tank.

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