CO2 & Algae coralation

Whiskey

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As I understand it:

Low (stable) CO2 (0-2ppm) = No Algae
High (Stable) CO2 (30-60ppm) = No Algae
But! Fluxuating CO2 or CO2 in the 15PPM range = Algae farm.

Does that mean that if I took a successful Low light tank which has never had algae and has good plant mass, then injected a random 15ppm or so of CO2 and let that fluctuate without making any other changes (Especially to the light) that I would start to grow algae?

Then if I pushed that same tank to a stable 40PPM the algae would go away but plant growth would increase?

I ask because I'm unclear what part Light plays in this relationship. Like, does a low light tank limit Algae by Light? Or is it the CO2? Why the need for low light? Is the plant damaged if we drive growth hard enough that CO2 is able to bottom out completely slowing growth and giving algae a foothold?

Thank you,
Whiskey
 

Tom Barr

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Well, I think high light pose some issues for many, if the CO2 is consistently stable and you have say 10-20 ppm and you have moderate to low light.............then things can do okay.

But if you have lower CO2...........and add lots of light, then this ppm will fall once you turn the lights on after maybe 1-2 hours.
Better to ask what would favor algae more and plant growth least?

that's where most get algae overall.
 

Whiskey

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That is a good question Tom.

In my mind Algae is simply a plant, a leaky one perhaps but a plant none the less. How about we open up for discussion what environments favor plants and don't favor algae?

I know that Algae requires much less nutrients than plants so Provided you have enough for plants then you have enough for algae.

I know that Algae is always loosing what it needs to live, and re-aquaring it where plants do a much better job of locking nutrients up.

What about CO2? I know it drives both plants and Algae, but does one get more benefit than the other?

What else?

Thank you!
Whiskey

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That is a good question Tom.

In my mind Algae is simply a plant, a leaky one perhaps but a plant none the less. How about we open up for discussion what environments favor plants and don't favor algae?

I know that Algae requires much less nutrients than plants so Provided you have enough for plants then you have enough for algae.

I know that Algae is always loosing what it needs to live, and re-aquaring it where plants do a much better job of locking nutrients up.

What about CO2? I know it drives both plants and Algae, but does one get more benefit than the other?

What else?

Thank you!
Whiskey
 

Tom Barr

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Most discussion/focus should be about growing plants. Algae is just a symptom of poor plant health/care.

I've not seen any observations that really falsify this.
If you have algae issues, then you are NOT taking good care of the plants.
Many folks want to avoid that fact and try to argue about it and find so called exceptions.

If you move the goal post enough and avoid taking care of the plants like you should, well.........that's a logical fallacy.
I think it really becomes an issue with the aquarist just being frank and honest with themselves. I've found little that helps other than focus on plant health and growth, general care.
I can scape over the long term with just about any species, any light level, any general style, without algae issues.

I do not use any one thing, but the things I do use and use in most all tanks are things I suggest to folks.
CO2 is the most trouble.
Light is 2nd.
Filtration, general care is 3rd, ferts are somewhere way down as long as they are adding some.

Algae are not even really in that list.
 

Whiskey

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I get where you are coming from, but in that case wouldn't 15PPM of CO2 be better for plants than no CO2 at all? Also, wouldn't more light always benifit the plants?

I'm not trying to be argumentative, I'm just trying to understand your statement better.

I have really struggled with BBA in my high light tanks, I'm doing fine now with dosing Excel, but that seems to be a crutch that I'm sure won't last forever.

My No CO2 tanks on the other hand with limited light are amazing! I know just what to do to fix problems in them, and the plants I can grow do great,.. I'd love to have that same success with the Higher light High CO2 tanks but so far it has eluded me.

Whiskey
 

Tom Barr

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Whiskey;130012 said:
I get where you are coming from, but in that case wouldn't 15PPM of CO2 be better for plants than no CO2 at all? Also, wouldn't more light always benifit the plants?

I'm not trying to be argumentative, I'm just trying to understand your statement better.

I have really struggled with BBA in my high light tanks, I'm doing fine now with dosing Excel, but that seems to be a crutch that I'm sure won't last forever.

My No CO2 tanks on the other hand with limited light are amazing! I know just what to do to fix problems in them, and the plants I can grow do great,.. I'd love to have that same success with the Higher light High CO2 tanks but so far it has eluded me.

Whiskey

Well, you would get more plant growth, but stability is now an issue.
At non CO2 enriched ppm's, the stability is part of the method.

If you could keep the CO2 steady at 15 ppm, then yes, you'd have better/more plant growth.

One issue there: as different plants have different light utilization relative to CO2 demand/uptake, if you have some species, say Hydrilla, and then you have others , say Cabomba, you will have the Hydrilla gettign all the CO2 quick, and the 15 ppm will quickly drop to 5 ppm or less after a hour or so at HIGH light.
But if you use low light, what's the issue here?

Hydrilla will still beat up the Caboma because hydrilla can use the lower light much better than Caboma can and if you do that............they you will take up the CO2. But at a moderately low light levels, you can balance this relationship somewhat. So the CO2 ppm stays the same, but both species grow well.
Some folks have managed to do this, but they think it's all their method rather than the plant species involved.

If you also trim the Hydrilla so it gets LESS light than the Cabomba, so the Cabomba gets 2x more PAR..................then this also works and evens things out.

But generally, at LOWER light values, the lower CO2 is fine, there's just not as much demand for CO2 at low light.
At high light, then you need to add more. Or if you have a lot of species and/or at different heights/PAR values

Stability for CO2 is like EI also, you can simply add non limiting amounts and take good care of the tank.
For weeds, this seems to be about 30-40 ppm, for some other species, it might be a bit more to keep it stable and all the plants operating smoothly.
 

Whiskey

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If one plant sucks up all the CO2 the PH should go up to reflect the current CO2 level, is that right? Or are other acids produced during the growth process that would depress that?

Does this mean that the core issue is the plant needs to always have more CO2 than it requires?
IE:
Lower light, means the CO2 needs are less, and it uses it at a lower rate so,.. 15PPM is plenty to ensure that the boundary layer around the leaf is sufficiently saturated to ensure the plant never needs more than it gets.

BUT!
As the light level goes up, needs increase, Now we need far more CO2 to ensure that boundary layer stays saturated at a level sufficient to supply the leaf with as much CO2 as it needs?

What happens to the plants if they are Limited by CO2 for a short period of time? Why does this affect the system so much?

I know that 15PPM Co2 is the best environment for growing BBA, but is it more than that? Like if the plants are not limited (IE Light is low enough) will BBA still take over a system at 15PPM C02?

Thank you,
Whiskey
 

Tom Barr

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pH should go up if the plants remove it.

CO2 will be higher in the upper parts of the water where there's good current, but lowest in the plant beds themselves.

Light is a factor, a huge one.

Varying the CO2 over a moderate range seems to cause the most issues with BBA, not at the higher end, nor at the lower end.
Algae ecology research suggest that in natural systems, 5-10 ppm is optimal for and flowing warmer streams for BBA.
 
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pH can also go down if plants are using carbonate as a source of carbon in non CO2 enriched systems, algae will be also benefited with water changes in those systems, I think because tap water contains some CO2. Algae can adapt easily, but plants don't. am I correct?
Regards

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pH can also go down if plants are using carbonate as a source of carbon in non CO2 enriched systems, algae will be also benefited with water changes in those systems, I think because tap water contains some CO2. Algae can adapt easily, but plants don't. am I correct?
Regards
 

Tom Barr

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Algae tend to respond more to environmental change, whereas plants do better where there's environmental stability.

But you still need to meet the needs of the plants also.
So plant focus, then stable within those ranges and you are okay.
 

fablau

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Yes, I agree that stability is paramount for plants to thrive. My algae issues disappeared when I stabilized my tank by giving stable ferts, light and most importantly, stable co2.