Backyard Aquaponics
A place to discuss aquaponics

lol

i'm off now anyway, have fun!

I think alot of you have overlooked the time old proverb " its the bubbles of nothing that are really something"

ROFL!!!!!!!!!!!!!!!!!!!

do they even make aerobar any more?

Ahhhh....

Pure Oxygen! ... Toxic!

Just a little note,
I believe that the bubble size of "air" is the issue in the amount of oxygen transfer. Understanding that too big does little, too little is potentially dangerous. And that air is only 26+% oxygen. Water will only naturally absorb a certain amount of ox., beyond that it must be "supersaturated".

Steve,
I believe the mistake with the quote you are arguing with "aeration only happens because of the surface agitation caused by bubbles", is quite the use of the word "aeration".

This is not necessarily "oxygenation". Aeration refers (normally, however, it is a term that is interpreted differently by many) to the more complete transfer of gases. This is NOT only oxygenation, which takes place during the contact time of the water with the "air(which hopefully contains oxygen)" (either in the rise of bubbles through water or through spraying of water out into the air.), but it is also the release of other gases from the water into the atmosphere. This second aspect of the "aeration" is definately caried out more with either surface agitation or some form of spray or splash, than it is through bubbles (of any size) and their contact time with the water (there is only so much that a bubble can absorb).

Many things ofcourse come into play, however, I think a good look at the orriginal creation will teach us much as to what we should be striving towards. THAT was the only case in our earths physical history that we had perfection. Ever since we got smarter than that, we have been messing it up.....

I guess this is where a different thread would start......

Couldn't agree with you more!

I assume you're inferring that "water fall" effect should be the primary goal? I also agree to that!

Just trying to make a point of order on the original statement.

Also agree with the distinction between oxygenation and gas transfer, but wouldn't it follow that water being able to take up O2 and gas off Co2 at the surface would hold true for a bubble containing air and surrounded by water? O2 would be taken up from the bubble while CO2 would be gassed off into the bubble?

All in all, i've done alot of agreeing with you.

Again, keeping it as close to nature is one of my fav. positions, thats why i love the solids retention and gravel beds so much. But we MUST prepare for cases where our "simulated" waterfalls fail due to power outage, and all in all i feel that bubblers as backups and make-ups are a good choice.

Have only just now come across this thread. Glad I didn't see it earlier, you sure did misrepresent things early on Steve with your 'only' statement. I am glad you corrected it . I am not a scientist and have no real interest in thinking about it in too technical a way, but I think we must remember we are talking about significant agitation to water surface caused by waterfalls etc. This is how water is aerated in nature and is clearly very effective (why else use paddle wheels). As for the thought that this concept is one that has been perpetuated (or maybe even coined) by the internet, I think that is unlikely to be true. I have had aquariums since I was a young child and remember reading exactly the same thing all the way back then, well before the World Wide Web.

I always assumed that the movement of a small molecule (in this case oxygen) from one body (air) to another (water) happens from the process of simple diffusion. If the O2 concentration in the air in contact with the water is greater than the O2 concentration in in water that is in the contact with the air (i.e it only happens where the 2 surfaces meet), then O2 will pass from the air to the water. There would be 2 ways to increase the rate of O2 exchange: 1. increase the gradient differential i.e have a higher concentration of O2 in the air compared to the O2 in the water, and 2. increase the surface over which it can occur. As mentioned above you can increase the surface area of the water by 1. blowing bubbles of air through it, or 2. disturbing the surface of the water. A waterfall or a river with rapids will have a greater surface area compared with the same volume of water sitting in a lake.

Oh oh, my wife just came in to inturrupt me and now I've forgotten my point

KE14 - I alwyas thought it may also have something to do with breaking the surface tension allowing the oxygen and water to diffuse more readilly - maybe that's just silly though.

Im not a scientist but surface tension shouldnt inhibit the transfer of O2, it is more of a physical property of the water but it is still only water. It isnt a membrane made of something else which the O2 has to pass through to get to the water.

silly

I think it would be impossible to poison a fish with too high O2 saturation if you are using just air and not pumping pure O2 into the water. The O2 concentration could only ever be equal to the O2 level in the air (25% or whatever someone previously mentioned) If the O2 level in the water was higher than the level in the air, the O2 would simply diffuse back into the air.

What would be the best method of diffusing O2 back into the air I wonder. Water aggitation I'd bet

VB i have infront of me a book published in 1992 that states that AP is only good for leafy green crops, and up until about two years ago thats exactly what you'd find regurgitated on any website that mentioned AP as well........

I agree its about the surface area, and 19 sq inches of surface area from a bubble column is a bit of surface area

The trout farm i pick up my fish from had a "paddle wheel" i always envisioned a paddle wheel as a graceful rotating device............the 2Kw barrel running at probably 1300rpm in the water sending a spray everywhere put that image to bed. Yeh, i bet it did a hell of a job airating

From my first post..................
Agitation is agitation and whether it is caused by bubbles or a power head,
the diffusion of gasses in and out of the water is a function of the
surface area exposed to the gas and the agitation in that surface. Aeration
adds the additional area of the bubble surface to the diffusion area.