# [Wet Thumb Forum]-Surface agitation in the planted low-tech tank



## flagg (Nov 29, 2004)

I just set up my low tech planted aquarium and I was wondering how much surface agitation is acceptable. I had to use the only powerhead I had availabe (an aquaclear 301 on my 10G) which is too strong I think even at the lowest setting. I attached some tubing to the output and put some holes in it to disperse the water over a greater area and to try to reduce some of the flow. Anyway, there is some movement of water on the surface even though the output hose is a good inch underwater and the holes face downward. So I guess what I'm wondering is, am I shooting for zero movement along the surface or is a little bit ok? Right now, there's not much movement, but it's def. there.

--ricardo


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## DataGuru (Mar 11, 2005)

As I understand it, disturbing the surface of the water gasses out more CO2. For instance, a venturi going full blast on a powerhead would be the most extreme example. Surface movement to me is less intense than surface agitation and probably results in less gas transfer. I'd say if the plants are growing well and the fish are happy, it's fine.


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## stcyrwm (Apr 20, 2005)

If you're not adding CO2 then you can have as much surface agitation as you want.

Bill


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## DataGuru (Mar 11, 2005)

Why do you say that?


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## stcyrwm (Apr 20, 2005)

> Originally posted by Betty:
> Why do you say that?


If you are adding CO2 then you don't want to lose it through surface agitation. That's where that guideline comes from. If you're not adding CO2 then your CO2 levels aren't high enough to have it be an issue and so you don't have to worry about it.

Does that make sense?

Bill


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## dwalstad (Apr 14, 2006)

> Originally posted by stcyrwm:
> If you're not adding CO2 then you can have as much surface agitation as you want.
> 
> Bill


A little surface movement is okay. If you've set up your tank with soil, your plants may have plenty of CO2 right now and your fish may need the surface agitation (to provide them with oxygen).

However, I disagree with your theoretical statement that trying to preserve carbon doesn't matter in a natural tank. Carbon is the limiting factor for plant growth in the natural tank. You don't want to lose what little you have (see page 100 my book).

The 301 might work okay with the adjustment you've made. Another thing you could do would be to just run it just at night and shut if off during the day. Let fish behavior dictate when you shut it off.

There's always more than one way to adapt!


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## aquabillpers (Apr 13, 2006)

> However, I disagree with your theoretical statement that trying to preserve carbon doesn't matter in a natural tank. Carbon is the limiting factor for plant growth in the natural tank. You don't want to lose what little you have (see page 100 my book).


Does the soil substrate contribute organic carbon in addition to some CO2?

Bill


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## dwalstad (Apr 14, 2006)

Yes. Soils rich in organic matter especially. As bacteria digest the organic matter, they release humic acids and other organic compounds into the water. This dissolved organic carbon also degrades, thereby releasing more CO2 into the water.

Natural decomposition of organic matter in the water and in the soil continously releases small amounts of CO2 (see page 60 in my book).


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## DataGuru (Mar 11, 2005)

interesting.

So do you think that during the day CO2 levels in the water of a natural planted tank would tend to be higher than the concentration of CO2 in the air?

If not, then would surface agitation during the day bring in more CO2 from the air?

At night I'd bet they'd be higher.


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## flagg (Nov 29, 2004)

> Originally posted by Diana Walstad:
> The 301 might work okay with the adjustment you've made. Another thing you could do would be to just run it just at night and shut if off during the day. Let fish behavior dictate when you shut it off.
> 
> There's always more than one way to adapt!


Ah, put it on a timer.... I hadn't thought about that. I think I might try that. Eventually I'm just going to switch to a smaller powerhead. Thinking about it, that seems like the best win-win situation. What about not having any circulation at all? Would that be detrimental to the fish or plants? I mean, have a tank of stagnant water... One thing I did notice is that the fish (guppies and cories) are a lot more active than before there was a current.

Thanks to everybody for your input!

--ricardo


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## Canlador (Aug 2, 2004)

I've run a couple tanks without filtration and only mild circulation. While the flora and fauna are very very happy (had some zebra danios spawn like crazy in one tank), I don't like the aesthetics of them. Stuff gets on the leaves and it just makes for a dirty looking tank.

So now I run my tanks with at least mild mechanical filtration. On my 10 gallon tank I've got a hob with the flow reduced and only a sponge in it. The plants didn't show any change between running the filter and not running it.

Like I said, for me it's an aesthetic thing.

/edit: I forgot to mention. I've got a 5 gal with 2 Flame Dwarf Gouramis in it with no filter or circulation. I'll have to take a picture because I swear their color is at least 5x brighter (especially the blue) than when I got them 6 months ago.


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## Miss Fishy (May 13, 2006)

I also have tanks without circulation, but I don't have problems with dirty leaves because there are many hungry snails and other creatures constantly cleaning them in their search for food! I have one tank left with an empty canister filter running on it, because whenever I switch it off the fish are less active so I think they need the circulation. In the other tanks, the fish are much happier in the still water. 

From Alex.


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## smilingfrog (May 22, 2005)

I've just put in an aquaclear 101 in a 33 gal tank, hoping that the circulation would be more than it is. My understanding of circulation in an aquarium is to improve the disolved oxygen for the benefit of the fish, but minimize loss of CO2 ie. no bubbling or surface agitation. 
Does it matter how much circulation you get in your aquarium if the fish appear happy?


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## flagg (Nov 29, 2004)

> Originally posted by smilingfrog:
> I've just put in an aquaclear 101 in a 33 gal tank, hoping that the circulation would be more than it is. My understanding of circulation in an aquarium is to improve the disolved oxygen for the benefit of the fish, but minimize loss of CO2 ie. no bubbling or surface agitation.
> Does it matter how much circulation you get in your aquarium if the fish appear happy?


From what I've read from the posts above and other ones, if the fish and plants are doing well there's nothing to worry about.


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## dwalstad (Apr 14, 2006)

Well put!

Good results are what we are seeking, not excuses for tinkering.


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