how airstones work

[wickedglass]

I've read on many forums about the use of airstones to increase the oxygen levels in a tank. Many people are of the impression that the bubbles the airstone/pump combo produces are actually the factor which increases the oxygen levels in your tank. This is actually not so. In standing water without any movement at all, the oxygen diffusion takes place naturally in only the top 5 centimeters. A filter which takes water from the bottom of the tank and re-introduces it at the top causes a roll-over effect in a tank if the outlet current goes along the top of the water. A spray bar further enhances this effect. Hang-on filters are good too, because the sheet of water which occurs in most brands takes up oxygen very effectively, and if the filter is strong enough to roll the water over, airation is also achieved.
Now we come to the humble, yet very effective airstone! Airstones will create water movement which takes the water from the bottom of the tank to the surface, where the oxygen absorbtion takes place, creating another instance of the aforementioned roll-over effect. The air diffused into the water by the stream of bubbles the airstone creates is actually rather minimal and has a neglible effect on the water's oxygen absorbtion.
Hope that helps gain an insight into what airstones actually do and how water is effectively oxygenated.

cheers,
Chris

[RichVic]

Thanks for that explanation - can you recommend a spray-bar at all?
I havent been able to find one on the main sponsors sites?
Much appreciated

[jim from sydney]

Thanks Chris...that is good value....Jim

[Ben]

A great Sticky for Discus keeping 101!

Thanks for the article Chris!

cheers
Ben

[wickedglass]

RichVic:
a spray bar usually comes with your canister filters. basically it's just a tube with holes in it that's connected to the filter outlet. Look in your local hardware for rigid non-toxic plastic tubing and drill some small gauge holes in it and seal off one end. insert the other end into your filter outlet tube, and voila! there's your spraybar. I was trained as a scientific glassblower, so I make mine out of glass if I need. handy for all sorts of fittings, actually ;)

[Merrilyn]

Well done Chris, that's a great article.

Feel free to write on any subject you wish. We're always grateful to receive articles written by members. :P

I'll put all these great articles together into a new forum soon, for easy reference.

[aj]

hi.. i'm kinda new here in this forum.. and i was just wondering.. do the bubbles that the air stone produce affect the water hardness of the water?

[Merrilyn]

Hi aj and welcome to the forum. The short answer to that question is "no". However the long answer is that sometimes the type of stone used to make the airstone can leech calcium into the water, and slightly increase the hardness.

If your water is hard, then I suggest you have a look at other things in your tank, like gravel or rocks.

A stimple test of the water from your tap, compared to the water from your tank, will show if something in your tank is turning your water harder.

[aj]

thanks ladyred.. i actually have a bear bottom tank for my discus.. but i placed tones of driftwood and a few java ferns... but thanks for your tip...

[lovenotthrowdiscus]

thanks for that post! alot of the things that might seem obvious
to the veterans are a huge info boost for us newbies.
thanks wickedglass!

i have 2 quick Q's?

where is the best place to put the spray bar? on the water edge,above slightly,below slightly?

i have 2 aqua one 1200's for my 6ft tank and my tank is at the setup nearly there exiting stage should i use both srpay bars or 1 with spray bay and the other with duck bill???

thanks man

[Nathan]

i put the spray bar above the waterline, so its pointing down and the flow is on hard enough for there to gas exchange which s a great way to help oxygenate the water. HTH

nathan

[wickedglass]

hi lovenotthrowdiscus,
In all my tanks I've set up the spraybars, on the same side as my filter intake, across and just under the surface level of the water (while my filter intake is at the bottom of the tank near the gravel). I do this because I don't like my tanks to be incessantly splashing and noisy. So, all those little jets on the spraybar have to do is to create a current to roll-over the water volume. As I mentioned in my original article, aeration (gas exchange) takes place in the top 5 cm of water and as long as this top volume of water is effectively rolled over by way of creating such a current, the water will be aerated.
Nathan mentioned pointing the spraybar down. This is another way of effecting roll-over.
I've included two very basic schematics (which I've drawn myself, so prepare to be dazzled by my awesome artistry). This is one way the flow of water can move through a tank to effectively aerate it.
In the first image is a view of the front of a tank, he spraybar is seen from the side (hence the spraybar is just a circle), and the roll-over is along the length of the tank, the water current is shown in dark blue.
The second image shows one way to position two spray bars to create a rollover across the width of a tank too long for a lengthwise current.
There's many ways to aerate the water in your tank and more fish generally means more aeration is needed. The only aeration I use in my big tanks is using rollover currents. I use airstones to create water-movement in only one of our tanks (7ft long) and that's more for distributing the heat from the 2 heaters evenly than aeration purposes.
(Just as an aside, another way of positioning your filters is to have the intake on one side and the outlet on the other, creating a stream ... personally I stay away from doing this, because I think there's no real roll-over and hence the aeration is not as effective)
Hope that helps somewhat
(everyone sick of the word roll-over yet?) :D

[Merrilyn]

Love the artwork Chris, and that insanely happy fish LMAO.

[lovenotthrowdiscus]

mate that is exactly what i was after!!!

thanks alot man.

i willdo this for sure in my tank.

keep up the art work too picasso lol (did help heaps)

[gro]

Gday wickedglass,

thanks for the info... i think i might be sitting at work next to one of your mates, he has a piece of glass from you i believe......does the surname stolz ring a bell!!!!!

gro

[Hassles]

Yeah OK, the airtstones don't add that much oxygen to the water but...what about diffusers :?: those airstones that emit a squillion tiny bubbles that look like a milky substance rising to the surface. Surely these would have to add just that little bit more. Anyone here using diffusers :?: How do you find them :?: What type do you have / once had :?:

[cityguy]

There is some controversy as to the efficiency of airstones versus the conventional powerhead system. Arguments can be made in favor of both systems, and both possess certain advantages and disadvantages. Among aquarists, the choice is very much a matter of personal preference, quite often discussed in internet forums. Below is what I feel about the effectiveness of airstone.. 8-)

Airstones provide life-esential oxygen to the fish and invertebrates in the water by keeping the surface of the water in constant motion. The action of airstones brings new water to the surface (air/water interface) in which the oxygen in the air can enter and from which harmful gases such as carbon dioxide can be disipated. It is important to note that it is at the surface, where the water is brought in contact with the air, that most dissolving of oxygen into the water occurs.

The concentration of available oxygen in water is extremely critical because there is so little of it in liquids. Air consists of over 20% oxygen, or 200,000 parts per million. Water is, however, entirely different. Normally water has only about 0.0006% or 6 ppm-which is 1/33,333 the oxygen supply in air! This means that fish and other "water-breathing" aquatic animals have had to evolve super efficient mechanisms for getting oxygen out of the water. They usually need a minimum of 4 ppm oxygen for good health, and preferably an optimum over 6 ppm. The conditions are even more rigorous for marine animals, because salt water may hold 2 ppm less oxygen than fresh water of the same temperature. The greater the amount of dissolved salts in the water, the less oxygen it will hold. To make the situation more complicated, the higher the temperature of the water, the less oxygen it can hold. There is about a 1 ppm difference in the amount of oxygen that can be in water at 70° F (21° C) and 86° F (30° C).

Airstones provide even temperatures throughout the aquarium preventing the development of thermoclines by keeping the water constantly mixing. Thermoclines are stratifications of waters into layers with a different temperature in each layer. In addition, during the night aquatic plants take in oxygen in their respiration and give off carbon dioxide. Under certain circumstances the removal of too much oxygen can cause the suffocation of aquarium animals such as fish. Airstones working constantly keep oxygen coming into the water and harmful carbon dioxide dispersing out of the water, maintaining the aquarium water in proper balance.

There are other facts that show how important good aeration is for the proper functioning of aquariums. As mentioned previously, carbon dioxide is removed from the water into the air relatively easily with the vigorous use of airstones. However, the passage of oxygen from the air into the water is much slower; it may take two hours or more to replenish sufficient oxygen into the aquarium water that has a greatly depleted oxygen level.