# Water Movement and C02



## MarkSchnell (Nov 7, 2011)

Okay, I'm not quite sure what the deal is with water movement and C02. It seems that I've read here that a lot of movement negates the benefits of C02 dosing. But, I seem to remember others talking about using powerheads to disperse the C02. 

So, which is it. What's the deal with water movement and C02? 

BTW - I'm doing DIY yeast and sugar C02 from two two-litre bottles. I have a Marineland Penguin 350 HOB. I'm getting healthy growth so far in my 38 gallon tank with two 36" T5 lights. The room gets a good amount of natural light too.


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## solarz (Aug 31, 2010)

You're thinking of two different things.

Water movement that breaks the surface will facilitate gas exchange, and thus allow CO2 to escape if you are injecting CO2.

The other issue concerns CO2 diffusion. I've read that CO2 diffuses slowly through water, and thus if your plant is growing quickly, they would get a CO2-free pocket around their leaves. Plants with broader leaves are more vulnerable to this than plants with narrower leaves. Thus, good water movement helps eliminate those pockets.


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## MarkSchnell (Nov 7, 2011)

Okay, that helps. I was also confused because I asked one of the guys at Aqua Inspiration if I needed to use a powerhead to move the water around he told me I didn't need to. I also noticed that their tanks there don't have a lot of water movement, or at least it didn't seem to me like they do.


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## solarz (Aug 31, 2010)

MarkSchnell said:


> Okay, that helps. I was also confused because I asked one of the guys at Aqua Inspiration if I needed to use a powerhead to move the water around he told me I didn't need to. I also noticed that their tanks there don't have a lot of water movement, or at least it didn't seem to me like they do.


U shouldn't need any extra powerhead if u have an adequate filter already.


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## charlie1 (Dec 1, 2011)

solarz said:


> U shouldn't need any extra powerhead if u have an adequate filter already.


Interesting logic- what would be an adequate filter for a 75 gln densely planted?
Regards


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## RCode (Dec 12, 2010)

Do you need some sort of aeration for the fish though?


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## Dave B (Feb 9, 2012)

Do u have a co2 indicator. And IMO the only thing u need to concern yourself with when using diy suger/yeast, is that you don't get any of that crap in the tank...............what a mess
But as long as u have an indicator and it is green, your fish and plants should be very happy together


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## MarkSchnell (Nov 7, 2011)

No haven't got an indicator yet. Hope to soon though.


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## Darkblade48 (Jan 28, 2008)

RCode said:


> Do you need some sort of aeration for the fish though?


No, you do not, provided that you are not injecting an excessive amount of CO2 and/or have an excessive bioload.


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## Zebrapl3co (Mar 29, 2006)

There are many types of way to diffuse CO2 into the water.
A power head near the surface of the water is undesireable for a planted tank because it creates surface aggitation which release the CO2 into the air.
However, there are some type of CO2 diffuser that requires a power head to drive the CO2 diffusion. They basically breakup the CO2 bubbles within a container. For these types of diffuser, you should put it low in the tank and avoid causing surface aggitation. These type of setup are usually for bigger tanks.
For most planted tanks, the water movement created by your filter (preferably canister) is enough and you don't need a power head. However, if you are not running any filter at all (as in a filteless setup), then you might what to run a weak power head to get some kind of water movement at the bottom of the tank.

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## solarz (Aug 31, 2010)

charlie1 said:


> Interesting logic- what would be an adequate filter for a 75 gln densely planted?
> Regards


I'm currently running an Eheim 2215 on my 79-gal starfire. I've got the intake and output set on opposite ends of the tank, and I feel that should provide plenty of water movement for the tank.

I am planting mostly vals and dwarf sags, so that further facilitates water movement. We will see how it works out.


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## Dave B (Feb 9, 2012)

MarkSchnell said:


> No haven't got an indicator yet. Hope to soon though.


I would get a co2 indictor, there like $20 at big al's. Then u will be able to see
if your setup is effiecient or not. IMO the first thing you should have bought.
Co2 is a good way to kill your fish if not monitored,but having said that diy yeast and suger isn't as big of a risk as pressurized c02.
So if you see your fish at the surface gasping for air, you should either cut back co2 or add a bubbler to help bring down co2.


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## solarz (Aug 31, 2010)

Before you go and spend money on a CO2 drop checker, you should test your water for pH and kH.

With those 2 values, you can find out your CO2 concentration in this chart:
http://www.rexgrigg.com/Algae1.html


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## MarkSchnell (Nov 7, 2011)

solarz said:


> Before you go and spend money on a CO2 drop checker, you should test your water for pH and kH.
> 
> With those 2 values, you can find out your CO2 concentration in this chart:
> http://www.rexgrigg.com/Algae1.html


Thanks for the great chart, actually I should say charts. There is a lot on that page. I need to get a test kit for sure. I'll be looking into that tomorrow.


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## MarkSchnell (Nov 7, 2011)

Dave B said:


> I would get a co2 indictor, there like $20 at big al's. Then u will be able to see
> if your setup is effiecient or not. IMO the first thing you should have bought.
> Co2 is a good way to kill your fish if not monitored,but having said that diy yeast and suger isn't as big of a risk as pressurized c02.
> So if you see your fish at the surface gasping for air, you should either cut back co2 or add a bubbler to help bring down co2.


My fish don't seem to bothered at all. I'm wondering if the fact that I'm using a Penguin HOB is helping to stabilize things. I try to keep the water level high enough so I don't get too much of a waterfall effect. But it is definitely breaking up the water surface.

I'm still new at this but what I know for sure is that the fish seem healthy right now and the plants are growing like crazy. I say right now because I know I need to monitor this stuff. So thanks for the heads up.


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## solarz (Aug 31, 2010)

The good thing about DIY is that you don't have to worry about it. It's very unlikely that yeast CO2 can overdose your fish. I run one 2L bottle of yeast CO2 on a 20-gal tank, and it's not even enough to drop my pH.

Which doesn't mean that yeast CO2 is ineffective either, as my plants grow very well compared with no CO2. Every bit of CO2 helps, you don't have to attain 30ppm to see good results.

Does your penguin HOB have a biowheel? I hear that thing isn't good for CO2. I would also raise the water level so that there isn't any surface breaking at all. How many watts of light do you have on your 38-gal? Are they T5NO or T5HO?


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## Darkblade48 (Jan 28, 2008)

Dave B said:


> Co2 is a good way to kill your fish if not monitored,but having said that diy yeast and suger isn't as big of a risk as pressurized c02.
> So if you see your fish at the surface gasping for air, you should either cut back co2 or add a bubbler to help bring down co2.


I would say the opposite; a working pressurized CO2 system is much less likely to kill your fish than a DIY system, mainly because a pressurized CO2 can be adjusted in a controllable fashion.



solarz said:


> Before you go and spend money on a CO2 drop checker, you should test your water for pH and kH.
> 
> With those 2 values, you can find out your CO2 concentration in this chart:
> http://www.rexgrigg.com/Algae1.html





MarkSchnell said:


> Thanks for the great chart, actually I should say charts. There is a lot on that page. I need to get a test kit for sure. I'll be looking into that tomorrow.


Unfortunately, while the pH/kH/CO2 relationship holds true theoretically, it cannot be used in an aquarium setting. This is because there are other factors in the aquarium water that will affect kH readings, giving false results.

This is why when using a drop checker, you cannot use tap, distilled or aquarium water, and must instead use a calibrated 4 dkH reference solution.


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## charlie1 (Dec 1, 2011)

Darkblade covered what i was going to post on the PH/KH chart.
On the subject of flow, there is a school of thought that a dense planted/aquascaped tank drastically reduces flow, this in turn hampers Co2 & nutrient distribution hence they promote more flow via pumps powerhead additional filter somewhere in the neighborhood of 10 to 12 times turn over, i`m one that practices this school of thought.
Regards


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## Boogerboy (Sep 23, 2008)

MarkSchnell said:


> Okay, that helps. I was also confused because I asked one of the guys at Aqua Inspiration if I needed to use a powerhead to move the water around he told me I didn't need to. I also noticed that their tanks there don't have a lot of water movement, or at least it didn't seem to me like they do.


FYI AI use higher than average filtration. I noticed the 50 gal tank in store was hooked up to an Eheim 2217, which does 265gph. This should be more than enough to distribute CO2 diffused through a traditional ceramic diffuser disc like the ones in their tanks (Hey, if it's good enough for Amano...)


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## mkblitz (Oct 12, 2011)

You don't want SURFACE agitation, but you do want water circulation (under the surface). I have a Hang Over filter and it is very poor for planted tanks, poor filtration, extremely poor circulation, however I decided to work aorund it instead of replacing it so I added a powerhead beneath the surface with a CO2 diffuser attached. It's a world of difference.


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