glutaraldehyde

[Sheraaz Essak]

Has anyone got any feedback on this product from "Aqua design" I usually look at the % of glutaraldehyde in a product I'm buying, as nothing was stated on the label or website, I emailed the company asking for some basic information, I.e the glutaraldehyde percentage used in their product. Unfortunately they weren't willing to disclose the % claiming their formula is a secret which has raised doubts on the effectiveness of their product.

Anyone that's actually used this and has some feedback, I'd really appreciate it, thank you in advance.

 

[Genahanney]

There have been experiments done using carbon 13 versions of glutaraldehyde based compounds and mass spectrometer of plant material reveals it contains carbon 13. Not sure if quantities taken up are meaningful but there is some science behind liquid carbon.

Can I read document of this observation?

 

[dw1305]

Hi all,

glutaraldehyde has algaecidal properties, and anything that reduces the algae burden in the aquarium will indirectly benefit plants through reduced competition for nutrients and light etc.

It definitely has "disinfectant" properties <"Liquid carbon dosing">. Stronger concentrations are used as a general biocide in hospitals etc. <"Stability of Glutaraldehyde in Biocide Compositions">. @Andy Pierce may be able to shed more light on its mode of action?

...... a strong association with the outer layers of bacterial cells, specifically with unprotonated amines on the cell surface, possibly representing the reactive sites, (from - <"Antiseptics and Disinfectants: Activity, Action, and Resistance">)

I assume that is also why you can get effects on <"obligate aquatic plants"> and bryophytes, they don't have a cuticle and are prone to damage by all <"oxidising agents etc">.

I'm mostly willing to give companies selling 'liquid carbon' the benefit of the doubt that they are not deliberately trying to mislead the consumer, but rather have taken some 'poetic license' with their description.

Personally I have no experience of them (and it isn't a product I'm ever going to use), but I'd probably put it in the "possibles" category. It is like all of these types of product, I just want the companies involved to <"show me the money">.

There have been experiments done using carbon 13 versions of glutaraldehyde based compounds and mass spectrometer of plant material reveals it contains carbon 13. Not sure if quantities taken up are meaningful..

Can I read document of this observation?

If they have bona fide scientific data showing their efficacy, surely they would want that in the public domain? This was what Clive (@ceg4048 ) had to say <"Seachem Flourish Excel">.

cheers Darrel

 

[Andy Pierce]

It definitely has "disinfectant" properties <"Liquid carbon dosing">. Stronger concentrations are used as a general biocide in hospitals etc. <"Stability of Glutaraldehyde in Biocide Compositions">. @Andy Pierce may be able to shed more light on its mode of action?

You can think of glutaraldehyde as short strap with velcro-grabbers on both ends. This double-sticky strap wanders around and grabs onto stuff tying it all up together. It turns out there are lot of biological molecules that don't really work if you tie them all up together so that's how it kills things. More details: the length of the 'strap' is slightly shorter than 1/1,000,000 of a millimetre (one nanometre), so really really small. That means it takes things are are already touching each other and forces them to stay that way instead of being able to drift apart. Fun molecular details: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2833024/pdf/f-66-00225.pdf

 

[dw1305]

Hi all,

You can think of glutaraldehyde as short strap with velcro-grabbers on both ends. This double-sticky strap wanders around and grabs onto stuff tying it all up together. It turns out there are lot of biological molecules that don't really work if you tie them all up together so that's how it kills things.

Thank you, that is perfectly explained for me.

cheers Darrel

 

[Genahanney]

You can think of glutaraldehyde as short strap with velcro-grabbers on both ends. This double-sticky strap wanders around and grabs onto stuff tying it all up together. It turns out there are lot of biological molecules that don't really work if you tie them all up together so that's how it kills things. More details: the length of the 'strap' is slightly shorter than 1/1,000,000 of a millimetre (one nanometre), so really really small. That means it takes things are are already touching each other and forces them to stay that way instead of being able to drift apart. Fun molecular details: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2833024/pdf/f-66-00225.pdf

Perhaps you can write in more detail what happens to glutaraldehyde when it gets into the water? What elements does it break down into and by whom (bacteria, plants) can these substances be consumed?

 

[Andy Pierce]

More important than what happens to it is how much gets added. I find this blog post from JBL to be persuasive that even with the highest level of glutaraldehyde you could realistically add without getting a lot of toxicity, and factoring in some probably wildly overly optimistic assumptions, the glutaraldehyde best-case could add the equivalent of 1 ppm CO2. I suspect the real value is much lower (essentially zero). I believe there are legitimate reasons for using glutaraldehyde in an aquarium - I use it for spot-treatment of hardscape and I go back and forth on whether to add it to the water column directly - but as a carbon source not so much.

 

[Genahanney]

More important than what happens to it is how much gets added. I find this blog post from JBL to be persuasive that even with the highest level of glutaraldehyde you could realistically add without getting a lot of toxicity, and factoring in some probably wildly overly optimistic assumptions, the glutaraldehyde best-case could add the equivalent of 1 ppm CO2. I suspect the real value is much lower (essentially zero). I believe there are legitimate reasons for using glutaraldehyde in an aquarium - I use it for spot-treatment of hardscape and I go back and forth on whether to add it to the water column directly - but as a carbon source not so much.

It is important for me to understand whether bacteria eat the decomposition products of glutaraldehyde..

 

[hypnogogia]

It is important for me to understand whether bacteria eat the decomposition products of glutaraldehyde..

I’m sure a quick google search would lead you to an answer. For example…

Aerobic and anaerobic metabolism of glutaraldehyde in a river water-sediment system - PubMed

Material balance studies of glutaraldehyde in a river water-sediment system demonstrate that glutaraldehyde preferred to remain in the water phase. Glutaraldehyde was metabolized rapidly under both aerobic and anaerobic conditions. The pseudo-first-order half-life of catabolism, based on the...

pubmed.ncbi.nlm.nih.gov

 

[LMuhlen]

While I don't expect glut to contribute significantly (or at all) to carbon absorption in plants, I feel the need to play the devil's advocate and add that it is possibly unfair to compare the "equivalent ppms of CO2" that the molecules could eventually generate if degraded, to what we add of CO2 gas. Most of what we add is wasted to the atmosphere, I imagine the waste to be above 90%, although that is a number pulled out of my imaginary hat.

IF the carbon from the glut or from any sub-product COULD be absorbed by plants in any way, it would be a much more carbon efficient way than adding gas to the water and having most of it dissipate. So this potential carbon availability would be able to be multiplied by 10 (using the 90% loss number for CO2), possibly reaching the less useless figure of 10ppm of CO2 gas equivalent.

But then again, probably none of this actually happens and it is all for nothing.

 

[Andy Pierce]

You're right that most of the CO2 gas is lost to atmosphere, but even after those losses the concentration in the water column is 30 ppm (or more) - that's what makes the drop checker change colour with injected CO2. It is that 30 ppm that is fully available to the plants, which is why the <1 ppm equivalent from glutaraldehyde doesn't make a meaningful contribution.

 

[LMuhlen]

The concentration of gas is no indication of how much the plants absorb, only how much there is available. If a plant uses 1g of carbon a day when there is 30ppm of CO2, it could be that it would absorb that same amount of carbon from the magical glut sub-products, even at a much lower concentration. The fact that most of the gas escapes is an indication that the plants don't use all the gas available, far from it. The absorption mechanisms for carbon from different sources would be completely different, so there is no way to compare directly. If the glut were to be decomposed all the way to CO2, then of course the comparison would be valid.

Maybe a valid comparison could be made if knowing how much gas we are injecting and knowing how much is wasted, regardless of the concentration during steady state. The used gas could then be compared to the weight of glut added daily, adjusted for the number of carbon atoms. But then again, there would be so many related unknowns, that when added to the high likelihood of glut having no way of being made available as a carbon source other than when fully decomposed all the way to CO2, it is all probably a waste of effort.

Still I think that saying that glut adds less than 1ppm of CO2 is unfair, it is apples and oranges.

 

[John q]

For me Clive sums up the Glutaraldehyde debate in this post.

Well again, the calculations cannot be verified just based on the atomic ratio of O and C in the GA compound.

It's highly likely that there is a series of chemical reactions that occur when a plant absorbs this compound. The atoms that form the CO2 may not even originate directly from the GA. We have no idea. Only Seachem and T. Barr have access to that information. You therefore cannot conclude that the GA equivalent CO2 production is 2ppm. It may be more than that , or it may be less. The computations are not valid until you know what the reactions are. How do you know for example that the compound isn't reacted upon by a Carbon carrying enzyme, and that the Carbon that results in the CO2 production does not originate from that enzyme instead of coming from the Carbon in C5H8O2?

GA typically kills cells by cross linking the cell proteins. C5H8O2 is a versatile compound that can morph into many very different substances just by the geometric shapes that the atoms can arrange themselves in.
GA starts out looking something like this:
View attachment 29442

But here is another chemical that is completely different but has the chemical same formula C5H8O2.
This compound is Acetylacetone. It has exactly the same formula as GA, but the atoms are arranged differently.
This shape is non toxic and is the basic building block of other useful compounds.
View attachment 29443

There are at least a hundred different shapes of this chemical formula C5H8O2. Depending on which arsenal of enzymes the particular species of plant has at it's disposal, the GA can be transformed and then broken or integrated into another compound. Some plants and algae may not have these enzymes and so the GA attacks the cell walls causing rupture, or it may inhibit the activity of some proteins like RuBisCo, causing an internal CO2 shortfall.

Furthermore, if there is an enzymatic reaction, we don't know what conditions or compounds inhibit or reduce the efficiency of the reactions, so yield cannot be calculated outside of that context. Temperature, internal cell pH and other factors may have an effect.

The CO2 and other residues caused by the addition of GA may originate from some totally unexpected process or reaction. The possibilities are endless, and the Molar ratios need to be calculated based on those reactions. So it's a gross oversimplification to assume that:
C5H8O2 -> CO2 because the behavior of the chemistry may not be as linear as that.

Sorry, but the calculations are meaningless without further clarification of the process by which GA is metabolized or neutralized.

Cheers,

The truth is we have no idea how adding glut exactly benefits the plants, they may well get an extra 1~2ppm of CO2 availability over the course of the day, or they may not. Maybe the carbon source is generated via some other pathway, or maybe it's not. Perhaps, and like most people assume glutaraldehyde's benefits are simply down to its algicidal properties.

Personally i suspect its a combination of all the above but agree it probably doesn't add any meaningful amounts (above 1ppm) of Carbon dioxide to the water column.

For the record I occasionally spot dose bba with Glutaraldehyde and for that it works (that's the algecidal effect in action) 🫡

 

[dw1305]

Hi all,

Maybe a valid comparison could be made if knowing how much gas we are injecting and knowing how much is wasted,

That is why I chose a floating plant for the <"Duckweed Index">, it removes one variable. Plants always have access to <"426 ppm of atmospheric CO2"> and it never runs out.

cheers Darrel

 

[tiger15]

Hi all,

That is why I chose a floating plant for the <"Duckweed Index">, it removes one variable. Plants always have access to <"426 ppm of atmospheric CO2"> and it never runs out.

cheers Darrel

426 ppm CO2 in air is expressed by volume. 1 to 30 ppm CO2 in water is expressed by weigh.

Unit conversion from by volume to by weight is not simple. Parts Per Million (ppm) Converter.

My calculation shows that 426 ppm CO2 by volume is equivalent to 826 mg /m3 or 0.826 mg/l by weight in air. So CO2 concentration in water is often higher than in air, but the diffusion rate to plant in water is much slower.

 

[hypnogogia]

426 ppm CO2 in air is expressed by volume.

Is it? Please explain.

 

[tiger15]

Is it? Please explain.

1 ppm CO2 in air is 1 cubic meter of CO2 in 1,000,000 cubic meter of air by volume under STP. It can be converted to 1.94 mg per cubic meter by weight in air using a complex formula.

 

[dw1305]

Hi all,

My calculation shows that 426 ppm CO2 by volume is equivalent to 826 mg /m3 or 0.826 mg/l by weight in air. So CO2 concentration in water is often higher than in air,

I'm <"really not sure at all"> about that at all. I think we are probably in <"Apples and Oranges"> territory, but I don't actually know. @hax47 or @Andy Pierce are probably your best bet for a definitive answer.

When you don't inject CO2 it is back to <"Henry' s law">, and the Duckweed Index was originally developed for low tech, before I knew that adding CO2 was a "thing". I can say definitively that low tech plants grow better with access to atmospheric gases.

Partially I think there is more to it because you can get a <"huge amount of dissolved CO2"> into a liquid under pressure.

cheers Darrel

 

[tiger15]

Hi all,

I'm <"really not sure at all"> about that at all. I think we are probably in <"Apples and Oranges"> territory, but I don't actually know. @hax47 or @Andy Pierce are probably your best bet for a definitive answer.

When you don't inject CO2 it is back to <"Henry' s law">, and the Duckweed Index was originally developed for low tech, before I knew that adding CO2 was a "thing". I can say definitively that low tech plants grow better with access to atmospheric gases.

Partially I think there is more to it because you can get a <"huge amount of dissolved CO2"> into a liquid under pressure.

cheers Darrel

There are many misperceptions on CO2 due to the choice of unit.

The atmospheric CO2 concentration is currently 422 ppm by volume. The pre industrial concentrations was 280 ppm by volume. The current atmosphere has roughly 21% O2, 79% N2 and merely 0.0422% of CO2 by volume

https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth's_atmosphere

The solubility (saturation concentration) of CO2 is 1450 mg/l at STP, and a lot higher under pressure. The amount of CO2 in water is not restrained by the solubility, but by the amount available in the atmosphere as determined by Henry Law. Using a Henry constant of 0.83, the equilibrium concentration of CO2 in water can be calculated to be 0.69 mg/l at STP.

https://en.wikipedia.org/wiki/Henry's_law

The point I’m driving at is that plants can absorb CO2 more efficiently in the atmosphere than under water not because of higher concentration, but higher diffusion rate in the atmosphere. Due to difference in diffusion rate, CO2 in air, unlike in water, can never be depleted by photosynthesis. Nevertheless, CO2 measurements in forests have shown seasonal and diurnal fluctuation to smaller scale due to photosynthetic activities.

 

[John q]

The point I’m driving at is that plants can absorb CO2 more efficiently in the atmosphere than under water not because of higher concentration, but higher diffusion rate in the atmosphere.

And this relates to glutaraldehyde because...?

 

[hax47]

I'm <"really not sure at all"> about that at all. I think we are probably in <"Apples and Oranges"> territory, but I don't actually know. @hax47 or @Andy Pierce are probably your best bet for a definitive answer.

The point I’m driving at is that plants can absorb CO2 more efficiently in the atmosphere than under water not because of higher concentration, but higher diffusion rate in the atmosphere. Due to difference in diffusion rate, CO2 in air, unlike in water, can never be depleted by photosynthesis. Nevertheless, CO2 measurements in forests have shown seasonal and diurnal fluctuation to smaller scale due to photosynthetic activities.

That's correct, the ppm unit is misleading. In air, it is parts (CO2 molecules) per million (million air molecules). In water, ppm means mg /l. So we can not compare directly the two ppms. The calculation seems to be right, I also get 0.83 mg/l for CO2 in atmospheric air. The diffusion rate is 10,000 higher in air.