Oxigenation Question - Backup air pump

[LJA]

I recently installed a cheap backup air pump to my drilled 55gallon which is designed to turn on and operate on battery power in the event of a power outage. I set the air stone up near the top corner of the tank, submerged only about 3-4 inches into the water. In the event that this must provide oxygen to the tank for several hours, will this placement be a problem? I'm trying to think of wether or not the dissolved oxygen will diffuse throuhgout the tank or if it will be ineffective, being that it is placed so high up and to the side. The only reason I set the stone up where I did is for asthetics.

this is what I bought: http://www.amazon.com/Penn-Plax-Sil...mp aquarium&qid=1464688772&ref_=sr_1_1&sr=8-1

 

[AB_reefer]

tagging along :fun4:

 

[pyithar]

if the power outage is only for a couple of hours, there won't be any problem imo. there'll be water movements at the surface from bursting bubbles so gas exchange can occur.

 

[Greybeard]

More water movement is better, if the airstone can be located near the bottom of the tank, it'll move more water around. Anything is better than nothing, so if this is the only place you can put it and be happy with it, it's fine.

Temperature, surface area, and stocking levels all make a big difference in oxygenation. My tank is fine for several hours with no water movement, but if you've got a tall, narrow tank, heavily populated, in a warm room, it can suffocate very quickly.

 

[ca1ore]

Agree that anything is better than nothing. Just remember that an airstone does not directly diffuse much O2, it functions primarily as a mechanical movement for the water. So, deeper in the tank is better.

 

[Sk8r]

I got through an 8 day power out by a) lowering temperature of tank and b) standing on a chair and dipping and pouring water into the tank every 4 hours (enough water to equal volume of tank). The bubble aeration does help, as does surface agitation. Tanks differ: my 54 or the 102 will go an easy 8 hours with no power. Fish load matters.

 

[smatter]

Procure a piece of rigid air line tubing. It makes it much easier to run down the corner of the tank or wherever you want it to go. It can be easily bent into any shape by warming it with a lighter. You don't even need an airstone on the end. Big bubbles really get the water and surface moving. Since you have a 55, just drill a small hole in the lip if your trim that holds the rigid tubing snugly. Insert the tube through the hole you drilled for a tidy secure installation.

 

[LJA]

Procure a piece of rigid air line tubing. It makes it much easier to run down the corner of the tank or wherever you want it to go. It can be easily bent into any shape by warming it with a lighter. You don't even need an airstone on the end. Big bubbles really get the water and surface moving. Since you have a 55, just drill a small hole in the lip if your trim that holds the rigid tubing snugly. Insert the tube through the hole you drilled for a tidy secure installation.

That's a pretty good idea, I may do something like that.

 

[LJA]

Agree that anything is better than nothing. Just remember that an airstone does not directly diffuse much O2, it functions primarily as a mechanical movement for the water. So, deeper in the tank is better.

Is this really true? I thought the rational behind air pumps/air stones was to introduce micobubbles, therefore introducing some dissolved oxygen into the water. I think we need a chemist here to chime in.

 

[mjstech]

I am not a chemist either, but i think it has to do with the amount of movement... the surface is your tank w x l. which is quite large. Micro bubbles will disturb the surface a bit and will introduce some O2, but it is the surface where it counts.

 

[OrionN]

For the same volume of air, the smaller the bubbles the higher the surface area. Small bubble is better than larger bubbles but any bubble and agitation of the surface will do.

 

[ca1ore]

Is this really true? I thought the rational behind air pumps/air stones was to introduce micobubbles, therefore introducing some dissolved oxygen into the water. I think we need a chemist here to chime in.

Seems common sense to me. If micro bubbles dissolved in the water, then folks wouldn't have trouble with them. That they persist supports the contention that any diffusion is likely minimal. I imagine there have been tests conducted.

 

[OrionN]

Surface area is the place where air exchange occurs. The air bubble does not dissolve into the water. Rather the O2 and CO2 (and other gases) diffused at the air/water surface so the concentration of O2 and CO2 In the air and in water reach equilibrium. How well this happen depends on the total surface area. Once the amout of surface area reach a critical number the tank water would reach equilibrium with the air. Any more surface area does not add to the amount of O2 or CO2 in the water. For the same volume of air the smaller the bubbles the higher the surface area over all.

 

[jmm]

Circulation is all that's important. Bring the oxygen-depleted water to the surface and the exchange with the air will occur. It doesn't matter whether the bubbles are small or large. They are moving too fast for oxygenation. It occurs at the surface.

If the tank has tops and is not completely open to fresh air, the air pump will create a positive pressure above the tank which will keep the air pumped out of all the small outlets and if the air pump's intake is in fresh air, the air above the tank will remain fresh enough to aid in the exchange.

Years ago, when undergravel filters were powered by airstones, people were convinced the air was being added to the water. When power heads were invented and used to power the undergravel filters people were suspicious and hesitated to do away with the air pumps. The advantages of the air-free powerheads as far as salt spray from popping bubbles and lower maintenance was soon realized however, and, at least in salt water tanks, air is seldom used.

The battery in the emergency pumps won't last long. The already dissolved oxygen in the tank would probably last longer. Have plenty of batteries if you expect a long outage. A battery powered propeller pump would probably be better.

 

[OrionN]

Confusing isn't it. Anybody can write anything on the internet and we won't know if the poster is 6 year old or PhD in Bilology or Chemistry.
Best of luck.
Have plan for power owtage, at the very least Batery operated air pumps with spare battery if needed. DC to AC transformer to convert car battery to 120 V AC also cheap and can save your tank in a pinch.
Better start now. there will be hurricanes this year in Florida, or Texas in my case.

 

[jmm]

Confusing isn't it. Anybody can write anything on the internet and we won't know if the poster is 6 year old or PhD in Bilology or Chemistry.
Best of luck.
Have plan for power owtage, at the very least Batery operated air pumps with spare battery if needed. DC to AC transformer to convert car battery to 120 V AC also cheap and can save your tank in a pinch.
Better start now. there will be hurricanes this year in Florida, or Texas in my case.

Or, in my case, a small trained monkey.

 

[jml1149]

Circulation is all that's important. Bring the oxygen-depleted water to the surface and the exchange with the air will occur. It doesn't matter whether the bubbles are small or large. They are moving too fast for oxygenation. It occurs at the surface.

Not confusing.

Gas exchange occurs at any water/gas interface. More bubbles = more surface area = more gas exchanged. It's the same reason running an outdoor line to your skimmer will help increase pH or you can reduce the pH of water coming into a calcium reactor via injecting CO2.

Agitating the waters surface does two things, removes any biofilm in stagnant water and increases surface area.

Running bubbles in a tube (small sponge filter in QT) generates flow because of the tube, I can't imagine an airstone in an open 55g tank moves much water at all.

 

[CStrickland]

When you use this sort of pump in an outage you aren't supposed to put the airstone on it. The large bubbles that the pump creates on its own will move the water better than the finer ones the airstone creates.

ETA: just saw smatter's post. What she said

 

[jmm]

When you use this sort of pump in an outage you aren't supposed to put the airstone on it. The large bubbles that the pump creates on its own will move the water better than the finer ones the airstone creates.

ETA: just saw smatter's post. What she said

Agree