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At one point I was  using my pump to stir up solids in the bottom of my tank.

 

Tonight, I thought I would look around and see if there was a venturi  that would work with the pump to add more air.

 

I stumbled on this video.    The pump is way to much power for what I  need, but, I am thinking it would cost me nothing to run an air  line down next to my pump input and see if I get any results.

 

This guy is putting some massive amounts of air in.

 

https://www.youtube.com/watch?feature=iv&annotation_id=annotati...

 

 

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Can you show us pictures Hal?  Or maybe make a basic diagram to show what you are describing.

There is a video of something similar on Affnan's site. Anytime you can break up the surface area of water, oxygen will be added so falling water is always an opportunity.

http://affnan-aquaponics.blogspot.com/2010/08/aeration-trying-to-ge...

Here you have it.  Water comes down in small pipe, enters large pipe, trapping and mixing in air that enters through large pipe's open end. Bubbles and water exit top opening, aerated water exits below without bubbles.

Hal

TCLynx said:

Can you show us pictures Hal?  Or maybe make a basic diagram to show what you are describing.

Attachments:

tip, you can post pictures directly into a post using the Img button which is right next to the link button on top of the post box.

And that little drain addition looks like a handy way to 1, contain some of the splashing and 2 help create a swirl action in the tank.


Thanx TCLynx. For helping me up the learning curve.  I do make use of that swirling action, which in conjunction with an uptake facing the opposite direction keeps the bottom of my round barrel pretty much clear of sediment.


TCLynx said:

tip, you can post pictures directly into a post using the Img button which is right next to the link button on top of the post box.

And that little drain addition looks like a handy way to 1, contain some of the splashing and 2 help create a swirl action in the tank.

This was my simple solution... 1 inch pipe with a T attached to 3/4 hose to my grow bed drain. It draws air in as the water drains. It is definitely quieter than letting the water just dump in the tank. Less splashing too.

Just a thought but what would be the effect of going from 3/4 down to 1/2 and then introducing air below the reduction?  Doesn't a venturi work by increasing pressure, instead of decreasing?  This has been in my plans to experiment with but one of many that I haven't gotten around to yet. 

If the pipe was smaller than the tube you would just have water coming out off the top of the pipe. I don't think this is a venturi... it just allows the water and air to mix as gravity accelerates and pulls the mixture down. I'm naming it the "NYC Bubble Drain" so I can be as famous as Affnan ;)


George said:

Just a thought but what would be the effect of going from 3/4 down to 1/2 and then introducing air below the reduction?  Doesn't a venturi work by increasing pressure, instead of decreasing?  This has been in my plans to experiment with but one of many that I haven't gotten around to yet. 

With venturi you need enough pressure pushing the water to overcome the drag of the restriction in order for the velocity to increase enough to suck the air in.  If you are draining by gravity, then you have to be careful with restricting the water since gravity might not be strong enough to over come that and you may just wind up with a drain that is too slow to keep up.

In other words, there is a price to be paid when using venturi, usually it uses up some of your pumping power to deal with the restriction and pressure to inject the air into the water and you do loose some of your flow.  So balance carefully what is most efficient/cost effective.  Venturi are way cool, but they are not always the best answer.


As I understand it, a straight setup, where a smaller pipe protrudes into a larger one open to the air at the back end, makes use of the Bernoulli effect to suck air into the water.  This could be tweaked and improved by varying the size of the pipes involved, but this setup worked well with 300 gph and I went on to other tasks. To answer George, IMHO if the output was restricted (for instance, if you put a  spray head at the end of the supply hose), and if your pump was powerful enough to continue pumping the same volume of water, the increased water flow rate at the nozzle would probably draw in more air.  In the real world, you would have to determine whether you still had an acceptable water flow, and whether the volume of air injected is increased.  In my setup, I am not willing to sacrifice water flow in this line: it is the throughput of the biofilter.

Not sure whether Johnathan's bubble drain has any advantages through fluid dynamics, but it should agitate the water and mix in air through turbulence, depending on the flow rate. When I have tried it in smaller diameter pipes, (as an antisiphon device) the water often gushes out the top as well as the bottom at first for a few seconds, until the weight in the water descending starts to accelerate the water that way through suction.  If the capacity of the pipe is greater than the amount of water entering the "T" then gravity will suck in some air as well.

The original post here and the video that goes with it is pretty impressive.  Discussion did touch on the energy required to operate this system, but my impression is that the air pump is the least efficient way to do it; and besides, I worry about contaminating the airstream with aerosol oil from the air pump and affecting the health of the fish.

FWIW there are of course other strategies for aeration which I'm not sure have been mentioned- waterfalls, sprays, and fountains which are ancient technology and require a minimum of tinkering and upkeep. I think that like "Tim the ToolMan Taylor" I have a tendency to go with difficult, complex, but interesting ways to solve some of these problems, maybe to impress myself and my friends,  but I need a tattoo on the back of my hand that says Keep It Simple, so I can focus on the goal, get 'er done, and go on to another problem.


Jonathan Kadish said:

If the pipe was smaller than the tube you would just have water coming out off the top of the pipe. I don't think this is a venturi... it just allows the water and air to mix as gravity accelerates and pulls the mixture down. I'm naming it the "NYC Bubble Drain" so I can be as famous as Affnan


George said:

Just a thought but what would be the effect of going from 3/4 down to 1/2 and then introducing air below the reduction?  Doesn't a venturi work by increasing pressure, instead of decreasing?  This has been in my plans to experiment with but one of many that I haven't gotten around to yet. 

 http://www.youtube.com/watch?v=j47XbRzCcNo&feature=related

here is a link that really works GREAT!

Here is the demonstration of the air from the video link above.

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