Backyard Aquaponics
A place to discuss aquaponics

Not a rigorous test by any means but....

I was going to measure the air injected into the water by both methods by collecting the air underwater in a conainer and timing how long it took to fill the container with air.

Instead I just took videos and photos of the two different methods.

First how they are connected.

Note there is still a restriction on the water jet caused by the step down to the nipple before stepping back up to the 32mm pipe. Without this the flow would be higher and hence even more air would be entrained into the water.

Second the results...





Please before anyone gets too tense the comparison depicted in these photos is meant to be a starting point and is NOT meant to be construed as proof that venturis are crap but they are

Interesting...have you tried Spa venturi's Stuart?

No I just did this this morning. I've got an old spa but I cant see how to get the venturies off it without destroying every thing.

Mind you the venturi in the photo is a mazzei venturi. Top quality venturi. The ones in spas look like the cheaper ones Aquasonic sell.

Thought spa's used an air blower?
Now try sticking your jet pipe down a larger pipe filled with bioballs.

Hi Sleepe, where the standard air blower attaches to the spa venturi, we just attached an open air hose to the above the water line and it just sucks the air in like a demon.

Nice small bubbles What size pump are you running on that?

Yes they work but try taking the venturis off and then re plumb so that you have a jet of water hitting the water surface.

Are you talking to me or Porter?

In anwser to your question if you were talking to me....

Well it would be nice to know both Stuart also wouldn't your venturi be creating bubbles a fair distance from the water so you would have perhaps small bubbles being created and not showing up as much at the outer.
I still agree there are better methods.

Davey Sump Pump D15VA-3

https://daveypumpsales.com.au/?p=351

Had to go out to the GH to check.

Does the water jet require extra power? Like another pump?

I thought the advantage to the venturi is that it can be piped into an existing system and use gravity/existing pump to generate air?

Actually it is the reverse.

The venturi puts a restriction on the pipe which reduces the water flow. The water jet doesn't have a restriction so the water flow is not restricited.

Operating a venturi is just a matter of rate of flow through the venturi. With gravity systems, like the pipe on a SLO, you don't have enough pressure/fall to create enough flow to generate the suction to get a venturi to work.

The idea is is you add a venturi to the end of the pipe coming from your pump and the air that the venturi sucks into flow adds oxygen to the water. Now that is what is happening but at the cost of reducing the flow into the FT. This comparison is too crude to show anything more than the number of bubbles created but it is my theory that if you analyse the amount of oxygen added via venturi as distinct from the water jet, fall or other method you get more O2 from the later methods.