Changes in Liquid Carbon concentration and algae

[NeilW]

As we know changes in CO2 concentration can induce algae.

I remember reading somewhere that a plants uptake of liquid carbon works in a different, more indirect way to CO2 gas injection so should be considered something completely different.

Therefore my question is if you stop dosing liquid carbon, assuming the system was balanced previously without carbon enrichment as a low-tech setup, will it result in algae in the same way as if you did a massive water change? Does liquid carbon become part of the CO2/nutrients/light environmental balance or could the system be fundamentally flawed and it was the algae killing power of the liquid carbon that was preventing an algae outbreak out and worked as a sort of 'crutch'?

I am currently dosing liquid carbon in my setup to encourage faster growth and doing roughly 20% water changes weekly to dilute the increase in organic waste. As a result of the above how would I go about scaling back down this liquid carbon input/water changes down to low-tech?

 

[ceg4048]

That's always a tough one mate. From a carbon instability point of view changing Excel dosages is exactly the same as any other CO2 transient conditions. The reason? Rubisco is still the CO2 transporter no matter the regime. The Rubisco levels always correlate to the CO2 availability. Under conditions of low CO2, more Rubisco is produce in order to maximize the transporting ability. CO2 uptake efficiency is therefore maximized under low CO2 conditions. i recall data which showed that under low CO2 conditions 50% or more of the protein within a leaf is Rubisco. When CO2 is high, you don't need as much Rubisco and there is a drop in efficiency. The Rubisco levels fall to somewhere around 47% of total leaf protein content.

So under Excel dosing, which equates to high CO2 availability (relative to non-CO2 addition), the efficiency is low, enzyme content is lower. if you then switch the Excel off, guess what? the leaf has to ramp up production of Rubisco to become more efficient due to low CO2. This could take a week or more during which time the Calvin Cycle backs up and you incur damage in the chloroplast tissues due to free radical and superoxide damage.

So plantrs living in a low tech, non-enriched CO2 tank are lean, mean and very efficient. They develop a very high CO2 uptake ability precisely because there is very little CO2 around them. Plants living in a high CO2 environment are overweight, sloppy slugs because they can afford to be. The CO2 levels are high so they don't have to try very hard. When you reduce the CO2 levels, whether that be less Excel or less injection, they struggle mightily because it takes a week or two for them to start producing more Rubisco.

To minimize this impact it might be better to slowly decelerate growth and give the plants a chance to ramp up their Rubisco levels. Instead of going from X millilitres Excel per day to zero, perhaps from X to .8Xml daily for a week then to 0.6Xml daily and so on.

As you are adding less Excel the algae killing feature is also being reduced, right? I would also consider adjustments to light intensity and/or duration during this period, and possibly reduce amount of water changes as well - maybe do the WC after the photoperiod?

It's a tightrope walk. No doubt about that mate.

Cheers,

 

[NeilW]

Thanks very much for your advice and knowledge mate . I've got the option of using either a 9watt or an 11watt lamp - currently I'm using the 9 on a 5 hour photoperiod with liquid carbon as I'm throwing caution to the wind since my algae recovery. My plan is to use the 11watt on an increased photoperiod with EasyCarbo on full steam with weekly WC's to get increased growth until I'm happy with how the tank looks grown out. Then I'll put the scaling down plan into action, including your tip of doing the WC after lights out. I've found it easy to store dechlorinated tap water in a container ready to go, which means by the time I come to use it its hopefully equalised with atmosphere with CO2 content. However when I'm dosing the liquid carbon I think I'll go back to using water out the tap to maximise CO2, and then use the stuff from the container when scaling down.

So the actual physiology of the plant changes based on the available CO2, so in effect does this mean the whole 'system' has completely changed since being low-tech with completely different mechanisms for using up available CO2 and nutrients? Am I understanding right that the plants find it easier to lose Rubisco (becoming 'lazier' as it doesn't have to work so hard to survive, meaning it can put more energy into growing other cells and not producing Rubisco proteins) but harder to gain the Rubisco back, as by then the whole physiology of the plant has changed? Pure speculation but does this mean that some plant species are more efficient at doing this then others as they may have different environmental conditions that change quicker locally?

 

[ceg4048]

Hi Neil,
While there are physiological changes to the Rubisco levels, the mechanism of the Calvin Cycle never changes. Rubisco is a CO2 transporter, kind of like a rail system. It delivers CO2 to the Calvin Cycle to interact with Ribulose Biphosphate (RuBP). The combination of CO2 + RuBP yields a type of phosphate sugar known as "triose-phosphate".

This sugar can either be turned into glucose and eaten immediately or it can be converted to starch for long term storage. That's where the Carbon from CO2 goes, to build chains of Carbon molecules we call Carbohydrates. The Calvin Cycle is the birthplace of all breads, cakes, sugars, fruits, pasta, crisps, chips and nuts.

So the only difference between low CO2 and high CO2 is that in high CO2 I can produce higher levels of this triose-phosphate sugar. Everything else works exactly the same. The difference is in this transportation system. If there is less CO2 out there then the strategy is to send more agents out there to capture as much CO2 as I can. If there is a lot of CO2 out there then, yes, I can be lazy about it because the probability of encountering a CO2 molecule is high so I don't need as many agents.

This agent Rubisco is described as a huge, lumbering enzyme. It operates thousands of times slower than other enzymes and it size and complexity means that it takes a really long time to produce. Also, to make things worse, Rubisco has a very difficult time distinguishing between a CO2 molecule and an Oxygen molecule. The term "Rubisco" is actually an acronym for the real name which is "Ribulose-1,5-bisphosphate carboxylase oxygenase". You can see in this name the expressions "carboxylase" which refers to CO2 and "oxygenase" which refers to O2. This makes the enzyme less efficient because CO2 and O2 actually compete with each other at the binding site. Each O2 molecule that gets captured means one less CO2 being turned into sugar.

I need this sugar because it is a form of energy storage. When I burn sugar I create an energy unit called ATP (Adinosine tri-phosphate). Just about any activity that occurs in plants and animals requires energy in the form of ATP. Thinking a thought requires brain cells to use ATP in some manner. Lifting a finger requires muscle cells to use ATP. For a plant, growing and carrying out all the various functions which are basically all chemical reactions require ATP. So low CO2 means low sugar production, which means low ATP availability and so this means low growth.

Going from low CO2 to high CO2 is easy. The Rubisco system in a low CO2 environment is already highly efficient so that sugar production and growth rate increases are almost immediate. Going the opposite direction though is problematic because you're basically pulling the rug from under the plant. The plant has to now employ the stored starch reserves to make up for energy shortfalls. Also the Rubisco system is inefficient so increased production has to be activated for a complicated molecule. If existing CO2 availability is lost overnight this can cause trauma. That's why I reckon if you reduce the amounts slowly and wait a week it gives the system time to ramp up Rubisco production smoothly with minimal disruption.

It should also be apparent why CO2 enriched tanks require more of everything else, like Phosphate and Nitrate, right?

Cheers,

 

[NeilW]

Finally got my head around that now I've read it a couple of times. Thanks again for taking the time to enlighten my poor brain.

When it comes down to it life on earth is so incredibly complex. Just amazing how something has evolved basically to use such elaborate chemistry to live. I'm guessing that's how we define something as 'living' by how the different molecules interact at such a minute level.

In practical terms then this means that I need to be patient to give my plants enough time to rebuild such a complicated enzyme. Is there anything that can be done to speed up such production?

Cheers again.

 

[ceg4048]

That's it mate. Infinitely complex. We could study this the rest of our lives and still only know enough to be dangerous.
That something as humble as a blade of grass is able to turn the gas in your breath to sugar....is a miracle.

As far as speeding things up, well, the only thing I can imagine would be to do an extended soft blackout, maybe for a week or so. By "soft" blackout I mean don't cover the tank or anything like that but just don't turn the tank light on. Leave only ambient room lighting. That would certainly deter algae even if the plants weaken a bit, they could just live off their reserves. The penalty is that they would lose weight and only slowly regain it when the light came back on. I think that the key is to use lower light than before, that will help a lot. Another thing you can do, which all low-techers ought to consider when the lights come back on is to keep a lower water temperature because cooler water retains more of the ambient CO2 in solution. High temperatures drives gases out of solution faster.

Good luck with it mate.

Cheers,

 

[NeilW]

So if I build the plants up to optimum health with no deficiencies so that energy reserves would be at their highest on the 11watt light and carbon, then introduce the 'soft' blackout and grin and bear it for a week before reintroducing the light at 9watts. Hows that sound for a plan mate?

I've never had the tank mega warm as the the species in my tank are mostly sub tropical so its between 22-23 degrees C - would that be good enough?

 

[ceg4048]

Yeah, that all sounds good mate. Lots of times when I do a trim and put the clippings in the sink as a holding tank that just gets ambient lighting. The clippings just carry on, although the difference might be that many of them are just thrown in and float. This should work though.

Cheers,

 

[NeilW]

Another quick thought you may be able to answer Clive: Does the majority of the daily reduction of liquid carbon happen in the photo period and is it mainly down to the plants processing it or mostly due to the half life of the liquid itself?

Just pondering.

 

[ceg4048]

From what I recall of JamesC's discussion about it, the degradation occurs rapidly once dosed so that part of it is significant evidently. I think the half life is even shorter than what I had stated originally. What the uptake rates are and what the actual CO2 yields/efficiency and so forth are I couldn't say with any certainty mate. Have you got some scheme in mind?

Cheers,

 

[NeilW]

From what I recall of JamesC's discussion about it, the degradation occurs rapidly once dosed so that part of it is significant evidently. I think the half life is even shorter than what I had stated originally. What the uptake rates are and what the actual CO2 yields/efficiency and so forth are I couldn't say with any certainty mate. Have you got some scheme in mind?

Cheers,

No scheme in mind, was only thinking of trying to do water changes with fresh tap and liquid carbon daily an hour before lights on to give it a boost.

I was mainly trying to get my head around the properties of the liquid itself - seems its much better at killing things but really inefficient at delivering carbon. It may be my ignorance towards chemistry but I'm surprised they havn't worked out something using DOC's.

 

[ceg4048]

...was only thinking of trying to do water changes with fresh tap and liquid carbon daily an hour before lights on to give it a boost.

Yes this always works...but aren't you wanting to convert the tank to non-CO2 enriched?
Gluteraldehyde is a disinfectant and it was used originally to clean hospital operating instruments, so that's it's primary function. We're the only lunatics that decide to use it for it's other properties. Who knows how Seachem actually discovered the CO2 enrichment properties. This is pure speculation, but they might easily have been trying to use it as the basis of an algecide product and discovered quite by accident that plant grew better with it...

The problem with organic carbon sources are that photosynthesis evolved to convert inorganic carbon to organic form, not the other way around. So you can feed organic carbon sources to bacteria and yeast so that they consume it and convert it to CO2 but the carbohydrates that the plant cells burn would have to have the CO2 by-product find it's way back to the chloroplast for entry into the Calvin Cycle - which may actually happen, I've just not seen what path it takes. In any case there's little use plants have for organic carbon sources which are external to the plant, which generally equate to pollution. In fact, that's why we do water changes, to get rid of excess DOC that the plants and animals excrete. I believe some algae are able to convert and use some fraction of DOC, which is all the more reason for getting rid of DOC. Too much DOC reduces O2 and suppresses bio-availability of macronutrients. Too little DOC, such as in new tanks, suppresses microbial activity.

Here a schematic which shows the flow of carbon components. CO2 (DIC) is imported and DOC (fats, oils, carbohydrates) is exported. I have no idea where the gluteraldehyde fits in this schematic except that conceptually, we'd have to consider that it effectively acts as if it were in the upper left CO2 circle.

Cheers,

 

[NeilW]

The plan is eventually to turn non-CO2 enriched but whilst I've got the flexibility and I'm around more I thought why not try and increase growth some more. However I now am now armed with the knowledge of how to reverse this back to low-tech

Don't worry I'll now stop with my relentless brain picking mate, thanks for explaining the ins and outs of it in simple terms. I always find it interesting to gain an insight as to how the whole system of an aquarium works so I can do something to help it reach its best potential.

Cheers again for your time,
Neil

 

[NeilW]

I missed that diagram the first time, was it added after? Great explanation.

So the DOC isn't used by the plant itself but is a waste product, but is still part of the health of the whole system as the bacteria use it to some degree. I'm guessing it would also be a good measure of plant growth - more growth = more waste or DOC. Higher tech = more waste. The penny has dropped. 8)

In a natural system where is the DIC introduced? How do CO2 hungry plants like HC fare in their natural environment?

 

[dw1305]

Hi all,
I'm interested in how glutaraldehyde works as a carbon source. Clive wrote:

Rubisco is a CO2 transporter, kind of like a rail system. It delivers CO2 to the Calvin Cycle to interact with Ribulose Biphosphate (RuBP). The combination of CO2 + RuBP yields a type of phosphate sugar known as "triose-phosphate".

Very true, and true of all photosynthetic organisms from Cyanobacteria (which interestingly have "carboxysomes" for concentrating CO2) through to "CAM" and "C4" plants, (which use PEP carboxylase to "capture" CO2 and feed it into the Calvin cycle).

So the DOC isn't used by the plant itself but is a waste product, but is still part of the health of the whole system as the bacteria use it to some degree. I'm guessing it would also be a good measure of plant growth - more growth = more waste or DOC. Higher tech = more waste. The penny has dropped.

This is largely true, although sources of DOC may be the tannins and humic acids that we add to the aquarium from peat, leaf mould, oak leaves etc. This is from Brett the "Skeptical Aquarist" <http://www.skepticalaquarist.com/docs/energy/decomp.shtml>

But some organic substances resist complete disassembling. They are transformed by bacterial action into humic substances, which accumulate in the water and also help create humus in the substrate. Humic substances dissolved in the water account for about half of the dissolved organic carbon. (The remainder is accounted for by transitory simple compounds in solution: carbohydrates, amino acids, peptides, carboxylic acid, hydrocarbons, and the like.) All these organisms that break down organic material are operating by aerobic metabolisms. In fact they require so much oxygen that when water is rich in organic substances that are in the process of being broken down, it may become temporarily depleted of oxygen.

In a natural system where is the DIC introduced? How do CO2 hungry plants like HC fare in their natural environment?

I think the answer for HC and probably most other plants with a "very high" CO2 demand is that they are probably not true aquatics, but emergents or plants from seasonally wet environments and naturally occur in a much more CO2 rich environment, namely the air.

cheers Darrel

 

[ceg4048]

Yep, the breakdown of the carbohydrates and other DOC is one reason high tech tanks are vulnerable because the bacteria use Oxygen to consume or to convert the DOC. Neil you're exactly right that higher DOC export is a direct measurement of plant productivity. But because we have a closed system we need to get that DOC outta there otherwise it interferes with productivity. That's why I go on and on so much about keeping the tank scrupulously clean. That's just another way of saying to rid the tank of all that DOC as much as you can. Detritus/mulm is the most abominable buildup and we find it in the substrate as well as in the filter media. It's rich in microbes and DOC but this is fuel for the microbes who then reduce it to ammonia and then other microbes oxidize that to nitrite->nitrate. As you have deduced, in low tech the DOC production rate is very slow. That's why you can get away with few water changes and why the nutrient uptake rates are so low. But yes, again, that's one indication that growth is slow.

As Darrel mentions, some high CO2 plants spend much of their time as emergent so they have high contact time with atmospheric CO2. Others may come from CO2 rich springs or from areas where high levels of microbial action produce dissolved CO2 in abundance. Bicarbonate (HCO3) is also considered DIC, so waters that might have a high bicarbonate content may evolve plants which have a strategy to convert bicarbonate to CO2. This is yet another incredible mechanism whereby the plant send Hydrogen ions (H+) out from the abaxial surface (the bottom of the leaf). H+ is basically acid and this converts the bicarbonate to CO2. The plant then uptakes this CO2. This mechanis is called "proton pumping" because a hydrogen ion has no electrons but simply a proton in the nucleus (or the nucleus may have a proton and an uncharged neutron.) The bicarbonate strategy is especially useful during times of very low ambient CO2 levels and only about half of our plants have this capability. That's why some do really well in low tech while other falter.

Higher tech = more waste. The penny has dropped. 8)

Excellent. I think you're ready for the "Jump" program. Tank, load us up!

Cheers,

 

[dw1305]

Hi all,

It's rich in microbes and DOC but this is fuel for the microbes who then reduce it to ammonia and then other microbes oxidize that to nitrite->nitrate. As you have deduced, in low tech the DOC production rate is very slow. That's why you can get away with few water changes and why the nutrient uptake rates are so low. But yes, again, that's one indication that growth is slow.

For me this is the major difference. A low tech. system is a system with less energy in it all around and therefore changes, both "good" and "bad" will happen fairly slowly. Development of both biofilm and mulm (benthos and periphyton if you are a scientist) are actually factors you want to encourage to some degree if you are low tech. Again I'll use the "Skeptical Aquarist" as my link.
http://www.skepticalaquarist.com/docs/water/humic.shtml & http://www.skepticalaquarist.com/docs/biofilm/devbio.shtml.

cheers Darrel

 

[NeilW]

Theres some excellent info in there guys, I reckon with a bit of editing and condensing this thread deserves a 'sticky'

 

[a1Matt]

Theres some excellent info in there guys, I reckon with a bit of editing and condensing this thread deserves a 'sticky'

:text-+1: