# Airstones in a low-tec



## leemonk (Apr 22, 2012)

Hey,

Is there a place for airstones in a low-tech tank?

If so, how should they be used?

Regards

Lee


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## roadmaster (Nov 5, 2009)

I might place the airstone on timer to run at night when plant's take up oxygen but only if fish stocking was maybe on the high side.
Otherwise plant's should produce enough oxygen during the day to carry the fish over till morning.(I believe)
I noticed fishes at surface of my low tech,non CO2, 340 litre at an hour before daylight when light from nearby window luminated the tank to where I could see this.
I then hid hydro sponge filter behind some wood, and placed it on timer to run one hour after light's off,until same time light's come on,and no more fishes at surface of a morning.


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## leemonk (Apr 22, 2012)

thanks for the reply!

Did it interfere with the plants at all.... in relation to removing CO2 from the water etc?

Regards


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## roadmaster (Nov 5, 2009)

leemonk said:


> thanks for the reply!
> 
> Did it interfere with the plants at all.... in relation to removing CO2 from the water etc?
> 
> Regards


Have not seen any negative effect on plant's after a couple month's.
Mostly slow growing plant's crypt's,anubia,but vals and water sprite still growing fast, or as fast as they can given low light,weekly fertz,monthly water change.


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## PlantedGuest (Mar 27, 2012)

I've been wondering about airstones, as well - how detrimental to the plant-life do you think leaving them on 24/7 is? Surface movement depletes Co2, correct?


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## Diana (Jan 14, 2010)

Surface movement equalizes the CO2, oxygen, nitrogen and other gasses with the air. Each gas has a particular level of how much it will dissolve in the water. If the water is undisturbed, the gasses will not diffuse very far into the water. At the surface the water will hold just the 'right' amount of each gas, whatever amount of each willingly dissolves into the water. 

Deeper in the water (undisturbed tank, remember) the water will hold whatever gasses are in excess from things happening deep in the tank. For example, if the fish are giving off CO2, then the water will be rich in CO2. If the plants are giving off oxygen, the water will be high in oxygen. If the plants are removing the CO2 faster than the fish produce it, the water will be low in CO2. 

The better water movement the better mixed the gasses are, the more even distribution throughout the tank. With gentle water movement the surface is not rippling very much. 
Usually better water movement also means more water exchange at the surface. Water from lower in the tank that might have high CO2 from the fish, or lower CO2 because of the plants will tend to give up CO2 if it is too high, or gain CO2 if it is lower than the 'right' amount. 

If the CO2 is high in the water, then increasing the surface movement will allow even more CO2 to leave the water. 
But if the CO2 is already depleted from the water then increasing the surface movement will add more CO2 to the water. 

Adding more vigorous water movement (strong air bubbler or power head, or raising the outlet of a filter so the water is more active) will make the gas exchange even more for two reasons. One is that ripples have more actual square inches of surface that flat water. The other reason is that this additional water movement usually means better circulation throughout the tank. So those odd corners where the water may be calmer with a low flow system now gets better mixed with the rest of the water, so takes part in the gas exchange better than before. 

So... If the water has plenty of CO2, you probably do not want to disturb it very much, just enough to be sure the CO2 is well distributed around the tank. 
If the water is very low in CO2 you can take advantage of the CO2 in the air by exposing more of the water surface to the air so it picks up CO2 from the air.


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## Couesfanatic (Sep 28, 2009)

Air stones are not needed. Pretty annoying IMO.


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## PlantedGuest (Mar 27, 2012)

Diana, thank you for taking the time to actually explain all that - I really appreciate it! I've been trying to understand this for quite some time!

Since I don't have any expensive high-tech equipment to monitor the Co2 levels in my tank - is there any way of figuring out if my tank is high or low in Co2? Since it's a naturally planted tank. . . should I just assume that it would be low, as Co2 is not being added - and so try to keep the water surface as calm as possible? From your explanation, it would seem that having the bubbler ON/creating MORE surface movement would be the best thing on the whole for any tank. I would assume that an even distribution of all of these things would be healthiest for the fish and the plants. However. . . everything I see says to keep the bubbler on only at night, if at all, when oxygen might be depleted, because the plants need all of the Co2 they can get in a low tech tank.


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## roadmaster (Nov 5, 2009)

I think that if there are enough plant's and not too many fish,then airstone,sponge filter,bubbler, in low tech is not needed.
I only run the sponge filter in low tech,NON CO2 injected tank, because I need to thin out some fishes (approx 75 in 340 litre).
If fishes were fewer,, and tank was moderately to heavily planted like mine,,then I am certain that plant's could produce enough oxygen throughout the day to hold the fish over with plenty of O2 till morning when plant's once again begin to produce O2.
In CO2 enriched (injected) tank, I would not use something that would off gas CO2 .
Or at least that's my thinking.


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## Diana (Jan 14, 2010)

Roadmaster has the right approach: If something is needed, then use it. If you do not need it, then skip it. 

Here are a few guidelines:
If the fish are gasping in the morning you probably need to run something at night. Something is adding CO2 or removing O2 in quantities that are making the fish struggle for oxygen. 
If the fish are gasping in the day run something 24/7. 
In either case, consider reducing the stocking level of the tank. 

What are you going to do if the power goes out and you have no bubbler or pump? That overstocked tank is going to become WAY understocked all too fast. :-(

If the fish are never gasping at the surface I would not think you need to add more surface agitation.


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## VivaDaWolf (Feb 5, 2012)

I've running airstones in my tank to create surface movement so that it doesnt get stagnant.. I dont have a lot of movement otherwise, exept for water coming down from the filter hose in one area- and it seems the top of the water is just less scummy with the bubbles.


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