# Surface agitation for non co2 injected tanks.



## keithy (Jun 8, 2010)

the filter can have a lot of benefits, as poeple have mentioned that there can never bee too much filtration. I think a HOB filter will work.

But I do not think surface agitation will get you any significant increase in co2.


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## iliketogolf (Feb 7, 2010)

Clint said:


> I read that if you aren't going to use co2 injection you actualy want good surface agitation to put co2 into your water.


I read the same post... 

I know surface agitation gases off co2, whether or not you're injecting it, so that comment doesn't make sense to me. Any feedback or clarification from others would be appreciated.


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## lauraleellbp (Feb 3, 2008)

iliketogolf said:


> I read the same post...
> 
> I know surface agitation gases off co2, whether or not you're injecting it, so that comment doesn't make sense to me. Any feedback or clarification from others would be appreciated.


Depends on the CO2 levels in your water.

In most non-injected tanks the CO2 levels in the air will be greater than those inside the tanks, so surface agitation can only help.


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## iliketogolf (Feb 7, 2010)

lauraleellbp said:


> Depends on the CO2 levels in your water.
> 
> In most non-injected tanks the CO2 levels in the air will be greater than those inside the tanks, so surface agitation can only help.


I lifted the following passage from another post in another forum (I believe he uses this forum also; name is Byron) - he supports the idea that increased surface agitation is detrimental to plant growth:

"Extraneous water movement is detrimental in two ways: CO2 which is extremely important for plant growth is driven out of the water faster, and oxygen is brought into the water at levels beyond what is good for the plants, which have more difficulty assimilating nutrients when the oxygen level increases. But the more significant aspect is the loss of CO2.

Submerged plants have difficulty obtaining enough CO2 in nature and in the aquarium; this fact is believed by many to be the reason for the inherently slow growth and low productivity of aquatic plants over terrestrial. It also explains why floating plants always grow faster than full-submerged plants--the surface plants can use CO2 from the air. Further, freshwater emerged plants have been shown to be four times more productive that submerged plants. The reason is because CO2 diffuses so slowly in water as opposed to air, and this limits the underwater plant's uptake of CO2 because the CO2 molecules don't contact the leaves quick enough to meet the plant's needs. Aquatic plants have to use enzymes to rapidly capture the CO2. When the CO2 levels in the water become depleted, these enzymes sit idle, so to speak, but the plant still has to provide energy to them. This results in a reduction in photosynthetic efficiency and therefore growth of the plant because energy is being wasted. Thus, anything that removes CO2 in however small an amount will likely be detrimental to the plant's growth. And filtration causing fast water movement will contribute to this detrimental state."


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## Hoppy (Dec 24, 2005)

That quote from another forum isn't accurate at all. First, the reason for having surface agitation (surface ripple) when you inject CO2 is to increase the level of dissolved oxygen in the water. That oxygen helps the fish withstand the CO2 you are adding to the water. Oxygen in the water will not adversely affect the plants, as far as I know. That surface ripple does cause more CO2 to be lost from the water surface, but that effect is easy to over ride by increasing the rate of adding CO2 - the bubble rate.

If you aren't injecting CO2, the primary source of CO2 for the plants will be the air. CO2 is extremely soluble in water compared to oxygen and nitrogen. So, water exposed to air will fairly quickly reach an equilibrium concentration, where CO2 is absorbed from the air and lost to the air at the same rate. Exactly what that equilibrium concentration is, I'm not sure, but some people believe it is about 3 ppm. The more water surface area is in contact with the air, the faster the equilibrium is reached, so water ripple or agitation can only help maintain the CO2 in the water.

If you use the Walstad method, using biologically active substrate, the decomposition of organic materials in the substrate adds CO2 to the water, more CO2 than is obtained from the air. (I believe Ms Walstad has demonstrated this to be true). With that method surface agitation isn't a good idea, since there is no way to increase the addition of CO2 from the substrate to make up for the added loss from the water surface.

Surface rippling is good with injected CO2, good with inert substrates, and bad with biologically active substrates.


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## plantbrain (Dec 15, 2003)

I've bred a few fish thus far in this tank:










As you can clearly see, there's ample current, and unlike most folks, I've actually critically measured the CO2 over an entire day with a data logger.

It does not change much.

The point of a non CO2 planted tank is reduced growth, so less CO2 is still fine.
Key point is stable low CO2.

This can go either way as far as current and results.
But I have little trouble with any algae and lots of fish and good breeding.

I see little merit in the lift comments as I've falsified them a few times now.

Regards, 
Tom Barr


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## farmhand (Jun 25, 2009)

plantbrain said:


> Key point is stable low CO2.


If you inject co2, and do a large water change, why does this drop in co2 levels and rise again not cause algae?


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## iliketogolf (Feb 7, 2010)

Hoppy said:


> If you use the Walstad method, using biologically active substrate, the decomposition of organic materials in the substrate adds CO2 to the water, more CO2 than is obtained from the air. (I believe Ms Walstad has demonstrated this to be true). With that method surface agitation isn't a good idea, since there is no way to increase the addition of CO2 from the substrate to make up for the added loss from the water surface.


I'll readily admit that I'm a noob when it comes to planted tanks (I converted from years of having cichlids). My question pertains to biologically active substrates and related CO2 levels. Isn't a mature substrate "biologically active"? 

Assuming the latter is true, isn't it logical that surface agitation would be a bad idea for a non-injected tank similar to being a bad idea for Walstad type tanks?


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## Hoppy (Dec 24, 2005)

iliketogolf said:


> I'll readily admit that I'm a noob when it comes to planted tanks (I converted from years of having chiclids). My question pertains to biologically active substrates and related CO2 levels. Isn't a mature substrate "biologically active"?
> 
> Assuming the latter is true, isn't it logical that surface agitation would be a bad idea for a non-injected tank similar to being a bad idea for Walstad type tanks?


No, by biologically active substrate I mean the fresh topsoil, complete with organics in it, that Ms Walstad uses and recommends. A mature substrate will have mulm built up on and in it, but that will largely be converted to inorganic compounds, so won't generate the CO2 that Ms Walstad gets. As I recall, she measured the CO2 levels in a tank or tanks, and found that her substrate does contribute a significant amount. Her reason for preferring a split photoperiod was to give the substrate time to replenish that CO2 between lights on periods.

But, I haven't done any testing that verifies any of this, so I can't say it is 100% correct.


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## Liquid_Pyro (May 26, 2010)

This is a very interesting topic, I have also been very curious about many of the things mentioned so far.

Thank you


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## roadmaster (Nov 5, 2009)

plantbrain said:


> I've bred a few fish thus far in this tank:
> 
> 
> 
> ...


 

Any views from the front of the tank in photo? Looks similar to Riparium where much CO2 would be available via atmosphere?
If the key point in non CO2 is maintaining low, stable CO2 (ie)no water changes, would not surface (agitation) as opposed to current just under the surface as photo indicates, be driving off what little CO2 may exist? To me, agitation would be such as water fall effect from HOB filter or sponge filter whereas current,, would be from possible spray bar,powerhead,etc just under the surface.
Also understand that in non CO2 tanks that what little CO2 is available assuming there are also fish, is from said fish and bacterial activity in substrate.
Are you suggesting that we could do away with a canister filter and just run a couple sponge filters or HOB filters with their water fall effect without driving off what little CO2 may be present? 
I believe this is what original poster was inquiring, and my sincere apologies if this is not so.


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## Clint (Oct 7, 2010)

roadmaster said:


> Are you suggesting that we could do away with a canister filter and just run a couple sponge filters or HOB filters with their water fall effect without driving off what little CO2 may be present?
> I believe this is what original poster was inquiring, and my sincere apologies if this is not so.


 I suppose i wasn't too specific in my original post. I am keeping my canister, but i was just wondering about adding surface agitation. That waterfall effect is what forces many little air bubbles into the water. When I have the water level flush with the return i just see current, no bubbles. Those little bubbles should contain both O2 and CO2. 

I've noticed when the water in my test tank gets low and the water is really trickling in, the plants in there seem to perk up slightly compared to normal. I have some Aponogeton bulbs in there that have sprouts, the sprout growth seemed to increase noticeably once I started hearing the trickling of the water return. Normally when I hear that I just top the tank off, but after hanging out with you guys in the forums I decided to monitor the plants and see if i noticed anything. (Ack, I'm turning into a plant nerd...:help: :hihi
The filter is just an old penguin biowheel 125, so when the tank is full the water surface is calm for the most part except in front of the water return.


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## kuni (May 7, 2010)

Diffusion doesn't work that way. If the level of CO2 in the water gets depleted due to plant uptake, more CO2 will successfully diffuse into the water. 

Increasing agitation simply provides more surface area for this to occur, which functionally means that with decent agitation, CO2 is getting replaced as the plants use it. Note that you still have "low CO2" overall here, but what little there is is getting replenished with atmospheric CO2.

With a traditional high-tech setup, you're bubbling more CO2 into the water than would typically be there, so diffusion hurts you as CO2 evaporates from the water and into the air. (Hoppy points out that you can counter this by simply increasing the rate of CO2 bubbling). 

The bottom line is that diffusion can help or hurt you depending on your setup. Surface agitation merely increases the rate of diffusion.


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## plantbrain (Dec 15, 2003)

The same is true for O2...so too little movement = too little O2.

Therein lies the trade off many seem to not to discuss and this leads to poor conditions for fish:thumbsup:

The same is true for non CO2 or CO2 enriched systems, low O2 is an issue as you reduce flows.

If some CO2 is lost, so what? With or without CO2 injection, it's not a real issue, you can simply add more if you use Gas, or it does not matter if you use non CO2.

This way the O2 is high always and at night as well.


Regards, 
Tom Barr


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## Hilde (May 19, 2008)

Hoppy said:


> Surface rippling is good with injected CO2, good with inert substrates, and bad with biologically active substrates.


Uncertain if surface rippiling good when injuecting Co2 for here read, by mossback, that If water in your tank is deficient in CO2, some of the CO2 in the air will diffuse into the water, until an equilibrium is achieved. The rate of CO2 diffusion thru a disturbed surface is much higher than the rate thru a still surface. But diffusion works both ways. If CO2 levels in the tank are higher than ambient, the excess will diffuse into the air, until an equilibrium is reached.


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## mossback (Aug 12, 2010)

If you are doing el natural, disregard my post -- it assumes a conventional substrate, and I should have said so. 

Hoppy's comment that surface rippling is good with injected CO2 is quite interesting. I read the entire post, and the point is that he can inject CO2 a lot faster than it can escape back into the air -- even with surface rippling. So he can maintain ambient levels of O2 via surface rippling, and elevated levels of CO2 by injecting more than enough to compensate for what's lost thru the surface. All at the rather minor cost of having to recharge his CO2 cylinder more frequently. 

To me, this approach makes more sense than what I have read elseware about how to do CO2, and actually answers one of my objections to CO2 injection. 

+1 for Hoppy.


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## rickztahone (Jul 20, 2009)

mossback said:


> If you are doing el natural, disregard my post -- it assumes a conventional substrate, and I should have said so.
> 
> Hoppy's comment that surface rippling is good with injected CO2 is quite interesting. I read the entire post, and the point is that he can inject CO2 a lot faster than it can escape back into the air -- even with surface rippling. So he can maintain ambient levels of O2 via surface rippling, and elevated levels of CO2 by injecting more than enough to compensate for what's lost thru the surface. All at the rather minor cost of having to recharge his CO2 cylinder more frequently.
> 
> ...


i believe there has to be a balance however. there is "rippling surface" and then there's "ripping the surface". If there is too much surface agitation i believe it might out compete the co2 injection rate (e.g. sump and such)


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## lauraleellbp (Feb 3, 2008)

"Rippling" the surface is still not actually "breaking" the surface. It's breaking the surface that will outgas CO2.

As I understand it, the point in Tom's tanks isn't really to "create the ripple," the point is to create good current/flow in the tank as a whole to encourage the best CO2 distribution possible. The visible ripple is mostly a "side effect" lol


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## plantbrain (Dec 15, 2003)

For non CO2, this should in theory, stabilize the CO2 to the highest degree.

I've argued that stability of CO2, rather than some absolute ppm, is the key.
Why do we not have algae in non CO2 tanks and also none in CO2 enriched systems a full 10-20X richer?

Clearly CO2 is a factor in algae I think it is safe to say based on results/observations, errors(unintentional experiments).

No water changes seems to provide good stability for CO2.
Soil based systems do have a larger AM CO2 concentration........it builds up all night....but we are not talking a great deal, maybe an extra 1-2ppm. This drops off and is no different than well circulated system after 1-2 hours max. Then after the 1st 1-2 hours, it's even less........

Now O2, the CO2 comes from where exactly at night???
Decomposition.

How? Aerobic bacterial respiration............this REQUIRES........O2.
So there is less O2 and more CO2. There's a price for using organic matter as a source of CO2.

In the high circulation tanks....there's virtually no differences btw night/day for CO2 or O2. For all the talk about the benefits of stability.......seems rather obvious in this context.

Both "work" it seems.

3 of the 5 tanks I have are non CO2/no excel etc.

Regards, 
Tom Barr


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