Venturi physics....

[Mikey]

When I built my pond I installed a stock tank to act as a settling chamber and veggie filter.  Water entered the stock tank from the top and exited just below the surface.  My son found a piece of ABS plumbing lying around and he attached it to the 2" PVC to act as a venturi and put more oxygen into the water.  It worked quite well.

Yesterday I finished converting the stock tank into a Skippy.  I still wanted the venturi attached but now the water coming into the stock tank would meeting resistance since it would be nearly 2 feet deep in the stock tank.  I was concerned that water would be forced out of the air hole in my ABS venturi.  I thought that I would need to add a 2' stove-pipe piece of PVC to the ABS opening where it draws in air. 

So when I turned on the pump I was pleased to see that water was not coming out of the 2' vertical extension.  I was also pleased to see lots of bubbles coming out of the T that was near the bottom of the stock tank.  When I looked down into the vertical stove-pipe I couldn't see any water.  I then removed this section of PVC expecting to immediately see water come gushing up out of the air hole......but nothing happened.  Water was contently flowing through the venturi and it was gurgling as it sucked air into the passing water.

I certainly don't understand the physics involved but I am pleased I don't need to use that stove-pipe section of PVC.   Here's the venturi doing it's thing...

[OldMarine]

Mikey,

Interesting set up. So far, how's it working as a skippy? How big is your pond?

[Mikey]

Rich: It's much too early to tell.  I have no biological action going on yet since I just started it.  It may take a while in this chilly water....  The pond is 2300 gallons.

[mascot]

Since I'm too lazy to search...can you post pics of your pond?  I don't know if I've seen the whole thing already...thanks.

[Mikey]

Here's the main part of the pond.  The stock tank (in the background and to the left out of sight in this photo) empties into a small pocket of water, 25 gallons or so and then flows into a very short stream then into another pocket of water, 15 gallons or so.  You can see part of the stream in the first photo.  These mini ponds, or pockets as I call them, both have bottom drains and they also act as settling chambers for fish poo...  Water leaves the last pocket and flows over a small waterfall located just beyond the bridge.  The water then flows under the bridge and back into the pond.

[Jonna]

Mikey, that's gorgeous.  I don't think I've seen a pic of your whole pond like that with a description of how it works.  Having bottom drains in those first 2 small ponds is brilliant.  I bet the skippy will do really well for you.