bubble wand placement?

[mark razmandi]

im not a big fan of bubbles in my tank but i do want to give proper aeration to my fish...my filter does not cause much disturbance in the surface so i have a rena 400 air pump....im under the understanding that the oxygen is mixed with the water when the bubbles hit the surface and pop....if this is the case, is it ok if i keep the wands about 2 inches under the surface so i wont have to see them all the time....will it perform just as well as it being in the bottom of the tank?

[mark razmandi]

anyone? please?

[FrontosaurusRex]

that is a real good question. i'm not a big fan either, but i have to keep one in the tank because my filters dont aggitate the surface either.

Does anyone out there know an answer?

[Somefishguy]

not sure oh the answer but to get rid of them all you would need is a powerhead with the outlet pointed toward the surface to get the agitation

[jughead]

i would guess that as the bubble makes its way through the water column,the oxygen
works its way into the water.if thats the case,the deeper the better.wheres all them chemical engineers when you need em.

[mark razmandi]

i actually read in an article about how the bubbles travel to the surface and once they hit the surface and burst the oxygen is incorporated in the water....i dont know which is true but i really need to know lol

[Matt in Houston]

I dont think the bubble bursting has anything to do with the process....its just additional disturbance on the surface.

The lower the wand, the more disturbance it will create as the bubbles travel faster to the top...and in addition it will help bring some of the deeper water up for gas exchange at the surface, and mix things up along the way for better circulation.

Instead of a bubble wand why dont you get a small powerhead like a koralia nano and point it at an angle toward the surface. I have one that I only use at night in my co2 planted tank and it works great...its small, quiet, and no bubbles needed. Here is a pic of mine...






Good luck!

[mark razmandi]

ill look into it...how much should i spend?

[PhishPhreek]

air exchange


This is my take on the air exchange situation....
May be wrong but I did take all those physics courses in college way back when.

Air is composed of many gasses, the major ones being oxygen, nitrogen and CO2. Each gas has a partial pressure and all of them add up to make air pressure.

Water has dissolved gasses, which in turn have partial pressures similar to the air.

All things being equal, the partial pressure of oxygen in water is equal to the partial pressure of the oxygen in the air and the same with nitrogen & CO2. But when the fish uses oxygen it drops the partial pressure of O2 in the water and raises the partial pressure of CO2. At the boundary between the air and the water these different partial pressures cause more oxygen to enter the water and the excess CO2 to escape into the air. Now you can see that at the bottom where Mr. Catfish lives the O2 is lower that at the surface because it cannot exchange (and the CO2 is higher) That’s why there are no fish at the bottom of the Rift lakes.

Bubble wands / air stones are used to lift the water on the bottom to the surface so that the gasses can more readily transfer back and forth. Yes there is some small transfer between the air in the bubble and the water but it is minimum compared to the water/air surface exchange.

For better O2/CO2 exchange the water on the bottom should be raised to the surface and sprayed or agitated to maximize gas/water surface area & exchange. I prefer air stones with small bubbles in sponge filters but some small critters (daphnia) get hung up in small bubbles and require large bubbles. I also use UG filters with power heads or foam filters on an extension tube with the power head at the surface. But I really love an HOB filter with a bio-wheel double oversized for the tank its in.

Then again, if you're into plants and CO2 injection, you want to avoid letting the CO2 out so no air stones or agitation should be used.

[mark razmandi]

This is my take on the air exchange situation....
May be wrong but I did take all those physics courses in college way back when.

Air is composed of many gasses, the major ones being oxygen, nitrogen and CO2. Each gas has a partial pressure and all of them add up to make air pressure.

Water has dissolved gasses, which in turn have partial pressures similar to the air.

All things being equal, the partial pressure of oxygen in water is equal to the partial pressure of the oxygen in the air and the same with nitrogen & CO2. But when the fish uses oxygen it drops the partial pressure of O2 in the water and raises the partial pressure of CO2. At the boundary between the air and the water these different partial pressures cause more oxygen to enter the water and the excess CO2 to escape into the air. Now you can see that at the bottom where Mr. Catfish lives the O2 is lower that at the surface because it cannot exchange (and the CO2 is higher) That’s why there are no fish at the bottom of the Rift lakes.

Bubble wands / air stones are used to lift the water on the bottom to the surface so that the gasses can more readily transfer back and forth. Yes there is some small transfer between the air in the bubble and the water but it is minimum compared to the water/air surface exchange.

For better O2/CO2 exchange the water on the bottom should be raised to the surface and sprayed or agitated to maximize gas/water surface area & exchange. I prefer air stones with small bubbles in sponge filters but some small critters (daphnia) get hung up in small bubbles and require large bubbles. I also use UG filters with power heads or foam filters on an extension tube with the power head at the surface. But I really love an HOB filter with a bio-wheel double oversized for the tank its in.

Then again, if you're into plants and CO2 injection, you want to avoid letting the CO2 out so no air stones or agitation should be used.

well in a desperate attempt to understand everything you said i figure i just need to put my air stones in the bottom of the tank lol...since mine isnt planted or anything...THANKS