Backyard Aquaponics
A place to discuss aquaponics

A couple of months back I was having a chat with a bloke I had just met by chance and it turned out that he was, by his own admission, an AP and aeroponics expert*. He went on to mention some significant work that he had been involved in for some large international organisations and government departments. In the course of the discussion he claimed there was a very real need to re-aerate water that had been through a pump, since the action of passing through a pump largely depleted the water of available oxygen for fish.
I hadn't heard of this before and now really want to dismiss it once and for all, but can't quite. If anyone knows this to be a myth or knows it to be a fact, please chime in.

* This chap seemed quite credible but I have not had his work claims independently verified.

This is a good read on aeration by Dr Wilson Leonard.


viewtopic.php?f=1&t=12204&hilit=wilson

Do tell... who was this "expert"????

Where does the oxygen go?
It cant magically dissapear

Probably gets inhaled.. as a result of the crop grown "aeroponically"...

PLJ, I can't find anything to support his comments, even searching through Curtin Uni's access to peer reviewed science journals around the globe.

In my mind I can picture a small amount of DO being displaced (due to rapid pressure increase) where a little bit of water comes in contact with the edge of the impellor. This may or may not actually occur, however even if it does, this would be an insignifcant fraction of the over all volume that moves through the pump.

Water is fairly incompressible so you can't just "squeeze" the oxygen out.

Increased barometric pressure increases the amount of DO.

So, I don't understand what he's basing his statement on - it doesn't appear to be actual science.

Yep... couldn't find anything in my references... or "googling".... that suggested anything to give the idea any validity...

I think his "theory"... is about as valid as his "claim" to expertise...

I like how PJ dropped this thread then took off for the day...

Haha. You are funny guy, Charlie - I kill you last!
Some of us actually have work to do outside , you know, where there are no computers? Not complaining coz I love it, but it was really good to come back inside as the rain started falling and find so many excellent and educated responses to my question.
Thanks to all of you for going to the trouble of drawing on your experience or even pulling out the reference books to help me get my head around this one. On the balance of your responses I would say that this claim has to go in the myth basket.
I don't want to name names, R'OZ, but I have his business card on my desk. Apparently he has worked for NASA on a big aeroponics project, which I promptly looked up since I hadn't previously even heard of aeroponics. It is an exciting area of development - have a look:
http://en.wikipedia.org/wiki/Aeroponics#NASA_inflatable_aeroponics
Even if my expert acquaintance is off the mark re the oxygen depletion of pumped water, he certainly knew his stuff, generally. At the time I bumped into him out the back of a warehouse, he was hunched over some conical drums and pipework with a team of gnomes creating a sophisticated looking vortex filter/biofilter setup. That was when I first saw an eductor working its magic and, of course, I have now incorporated one into my big concrete tank system. My expert uses eductors for mass water movement and to compensate for the (real or imagined) loss of oxygen in the systems he designs.

(It has taken quite a while to type this due to having a 6 hour old rejected chick in my hand - long story.)

Even if some oxygen did come out of solution there is a good chance it will just be dissolved again by the time the water reached the end of the pipe.
A possible way to test this would be to put the exit pipe underwater and some sort of clear bottle/bucket over the exit so that it would catch any "un-dissolved" oxygen that would now be in the form of bubbles. Even if the bubbles were so small and few that they were hard to see, the bucket might catch them as they rose (it would have to be set up correctly).
That's my uninformed opinion

Whoa... who would have thunk it....

A venturi... to add more oxygen into the water....

I'm surprised that in all the years of this forum.. that no one has ever thought of it...

Aeroponics certainly makes sense as a methodology.. in space... compared to other methods, most of which are either just impractible, or just undoable...

But even in hydro... commercial and backyard.... aeroponics was flicked years ago after a brief rush of interest...

It's resurfaced a bit recently... even in a few aquaponic contexts (all essentially failures).... but particularly in relation to mist/foggers... and cloning... on the weed forums..

What are your theories on why it was discarded ?
Too capital/energy/labour intensive?
too troublesome perhaps ?

Really? Thats weird...
So your saying there is life outside of this forum? I think your having me on..