Can a weak air pump still pull water from the deep if it's a long tube below?

[knifegill]

I've got this 5' acrylic column and I'm thinking of setting it up, but I want it to be air-driven for $ reasons. If I put an airstone in the top, say, 8" of a 3/4" plastic tube that extends to somewhere near the bottom, will that top 8" of pull at least bring water from the bottom to the top? Obviously I'm not looking for intense filtration here. But is this idea sound? Isn't this how some of those recirculating gravel vacuums work?

 

[skjl47]

Hello; If I understand the potential setup, then the bubbles from the stone should generate a current flow in the column. The strength of the air pump will determine how deep an air stone can go and still produce bubbles. Air pumps have weakened to the point of only being able to generate bubbles a few inches below the surface for me. I would place the end down as deep as possible while still getting a good flow of bubbles. This generated a current flow, tho not as strong as when deeper.

One other thing I do is to eleminate the air stone or diffuser at the end of the air tubing all together and just have the tube with an open end. The bubbles are bigger but there is less restriction and this works quite well. A way to hold the end of the tube in place will be needed.

So yes, I think you will get some water movement in the column and it may be more than enough.

 

[Clay]

It will likely only pull/circulate from the depth the tubing sits.

 

[knifegill]

Ah, sounds good to me. If it pulls from the depth that it reaches, then there will be flow to replace that water. I can easily extend the tube to nearly the very bottom, thereby ensuring that all the water has to make the trip and back down again eventually. Probably not something I'm going to do in the next few days. But when there's a little more space in the living room I might set it up with pics.