Will Carbon from KH generator lost to atmosphere?

[CThompson]

Air stones causing vertical currents will facilitate the water’s CO2 to access the surface and be lost to the atmosphere as it is volatile and easily lost this way. It is my general practice with a planted tank, or a tank with lots of plants, to maintain as much CO2 as possible, not to use an air stone.

CO2 can come from the addition of CO2 by artificial means, from the biological processes of fish and bacteria and plants too.

It is my understanding and correct me if I’m wrong, that the carbon in KH generator can be accessed by the plants for their CO2 needs as well. The problem with KH generator is it will push the pH past 7, which has other negative issues related to best conditions required for plants.

However, we have available a KH product called KH Neutral, which will not allow the water to go beyond pH 7, but will still buffer the water.

Please confirm two points, can plants get their CO2 from a KH product?

And if the CO2 available to plants is in such a form, will it be blown off to atmosphere with air stones causing carbon in KH Neutral (or the standard KH generator for that matter) to be lost when in contact the surface?

I believe the answer to the first question is yes, plants can access the carbon from a KH product. And I don’t think that the carbon will be lost to atmosphere as it does with the biologically produced CO2, however, it is this main latter question that I would like to have confirmed or denied.

Please add your comments.

Thanks.

[gingerbeer]

I have certainly heard the kH high argument before and believe that it will sustain plants to a degree.

I beleive that it depends on the plants. Some plants just need more than others of the three basic requirements, light, CO2 and fertiliser.

I would suggest if you are serious about plants a DIY Co2 generator - coke bottle sugar yeast - is a more effective and cheaper solution.

[Noddy65]

Good question Craig

The answer is like most thing...yes and no...some species can do it, most need free carbon though....

The complication is that the process called biogenic decalcification can DRAMATICALLy increase your ph to lethal levels

Heres some cut and pastes from THE Krib

Plants like Elodea, Najas, Eigeria, Ceratophyllum, and Vallisneria are able

to utilize the bicarbonate ion, HCO3-, They remove CO2, leaving behind

OH-. The high pH created causes precipitation of calcium carbonate on the

leaf. The increased OH- drives the equation, HCO3- -------> H+ + CO3-- to

the right. The H+ combines with the OH- to form H2O, and the CO3--

combines with Ca++ to precipitate out as CaCO3.

The sandy layer on the leaves is calcium carbonate. Anacharis ( called

Egeria densa in M=FChlberg.s book) is capable of utilizing the bicarbonate

ion. It takes in bicarbonate, HCO3-, keeps the CO2, and leaves behind OH-.

In strong light, this process can create enough alkalinity at the leaf

surface to precipitate calcium carbonate, CaCO3. As long as your pH is OK,

I wouldn't worry, but you should keep close watch on the pH. I once saw

that my zebra fish in a tank with 3 T12 fluorescents and a lot of Anacharis

looked a little sick. I took the pH and found it to be 9.6. I added some

CO2 and the zebras looked a lot happier. Plants like Elodea, Najas,

Vallisneria, and ceratophyllum that can utilize the bicarbonate ion can

raise the pH in well-lit aquaria to almost lethal levels for fish.

Full link and discussion:

http://www.thekrib.com/Plants/CO2/decalcification.html

Mike

[CThompson]

Good question Craig

The answer is like most thing...yes and no...some species can do it, most need free carbon though....

The complication is that the process called biogenic decalcification can DRAMATICALLy increase your ph to lethal levels

Heres some cut and pastes from THE Krib

Plants like Elodea, Najas, Eigeria, Ceratophyllum, and Vallisneria are able

to utilize the bicarbonate ion, HCO3-, They remove CO2, leaving behind

OH-. The high pH created causes precipitation of calcium carbonate on the

leaf. The increased OH- drives the equation, HCO3- -------> H+ + CO3-- to

the right. The H+ combines with the OH- to form H2O, and the CO3--

combines with Ca++ to precipitate out as CaCO3.

The sandy layer on the leaves is calcium carbonate. Anacharis ( called

Egeria densa in M=FChlberg.s book) is capable of utilizing the bicarbonate

ion. It takes in bicarbonate, HCO3-, keeps the CO2, and leaves behind OH-.

In strong light, this process can create enough alkalinity at the leaf

surface to precipitate calcium carbonate, CaCO3. As long as your pH is OK,

I wouldn't worry, but you should keep close watch on the pH. I once saw

that my zebra fish in a tank with 3 T12 fluorescents and a lot of Anacharis

looked a little sick. I took the pH and found it to be 9.6. I added some

CO2 and the zebras looked a lot happier. Plants like Elodea, Najas,

Vallisneria, and ceratophyllum that can utilize the bicarbonate ion can

raise the pH in well-lit aquaria to almost lethal levels for fish.

Full link and discussion:

http://www.thekrib.com/Plants/CO2/decalcification.html

Mike

With KH neutral, the pH can't go over 7 Mike, so from my understanding, I won't have to worry about a rise in the pH to dangerous levels due to biogenic de-calcification as you explained.

I was aware that ribbon grass can do okay in alkaline/African water due to it's ability to access carbon from the water's KH, rather than from CO2.

If this ability is species dependant, how will anubis and bolbotis go with obtaining their carbon from KH neutral? These are the two plants in my little octagonal tank.

And the second part to my question was the loss of this carbon to the atmosphere. Is it like CO2 bleeding out when contacting the water's surface? Or is the carbon in Kh generator locked into the water and not able to disparate if it comes into surface contact.

This little octagonal tank, was set up for the anubis. Recently due to house extensions, the maintenance has gotten a little tardy (to say the least), and it has always had trouble supporting many fish without added oxygenation (air stone). I want to add some more fish (did in fact) to tackle the algae, and something pretty for me but also wanted to add some air for the fish, but not detrimentally affect the plants. Hence my question relating the loss of CO2/carbon through the tanks water surface.

Can I add an air stone without losing the carbon from water which has had KH added to it?

Thanks for the time replying

[Noddy65]

Hi Craig

My gut feeling is that since the carbon is bound (ie not free carbon like adding CO2) so the amount of surface agitation will make little difference.

You can also add things like Seachem Excel or the Dino range (from Aquagreen, but Im not sure if its still on the market) to add a soluable source of carbon...the nice thing is that these products can also help reduce algae.

I remeber that tank when i was at your house a few years ago....

The other thing is that anubais often have low carbon requirments (although it can help) and that the amount of light can be a limiting factor, you can add all the carbon you like but with low light the plants wont make much use of it.

To reduce complications in your life have you tried 6 months with and external carbon source and 6 months without and monitor the growth of the plants...it may make little difference?

Mike

[CThompson]

Hi Craig

My gut feeling is that since the carbon is bound (ie not free carbon like adding CO2) so the amount of surface agitation will make little difference.

You can also add things like Seachem Excel or the Dino range (from Aquagreen, but Im not sure if its still on the market) to add a soluable source of carbon...the nice thing is that these products can also help reduce algae.

I remeber that tank when i was at your house a few years ago....

The other thing is that anubais often have low carbon requirments (although it can help) and that the amount of light can be a limiting factor, you can add all the carbon you like but with low light the plants wont make much use of it.

To reduce complications in your life have you tried 6 months with and external carbon source and 6 months without and monitor the growth of the plants...it may make little difference?

Mike

I agree that the anubias is low nutrient, as is the bolbitis. However, there are a lot, as small leaved as the plants happen to be, their requirements will add up. Do you know Liebig's Theory on plant growth? Plant growth will be determined by the one factor present at a minimum (from memory that's how it goes anyway). That means, light or nitrates or any single factor present at a minimum can limit their growth. CO2 is another one. Being low requirement means that they need less, but still available

I use the KH neutral to prevent pH drops, more than as a plant carbon source, that's just an added benefit. With the introduction of extra fish to the tank, and the want to add an air stone, I realised recently that maybe the carbon here can't be blown off as CO2 is. I have used the product for some years, but this bi-benift has only just popped into my head Hence my question to see if I was thinking straight.

Thanks again for your answer Mike, appreciated.

Craig

[mattrox]

"Calcium bicarbonate is many times more soluble in water than calcium carbonate—indeed it exists only in solution.

Some of the HCO3– combines with H+ in solution according to:

H2CO3 <=> H+ + HCO3– Ka1 = 2.5×10−4 at 25 °C

Some of the H2CO3 breaks up into water and dissolved carbon dioxide according to:

H2O + CO2(dissolved) <=> H2CO3 Kh = 1.70×10−3 at 25 °C"

The above is from http://en.wikipedia.org/wiki/Calcium_carbonate

SO the answer is yes.... Since Carbonate is in an equilibrium with carbonic acid and carbonic acid is in equilibrium with dissolved CO2 and surface agitation reduces CO2 concentration in water, it can be lost to the atmosphere.... To what extent is another question but, under acidic conditions the CO2 is more likely to be off-gassed