# Is there any mention of using glutaraldehyde to enhance plant growth in academic lit?



## Fortuna Wolf

pretty much the title says it all. 
I did some searches on pubmed, jstor, etc. There's some mention of glutaraldehyde's effect in higher dosages (say 2%) on things like phytochrome and nuclear acid phosphatase - basically how glutaraldehyde can hurt plants. They're pretty obscure too, not often cited. 

But, according to seachem and you (the forum collectively) in addition to a mild algecidal effect dosing glutaraldehyde to .5-2 ppm has a beneficial effect on plants, increasing growth. Has this ever been studied in a lab environment or published academically?

What sort of effect do you see from it? Essentially increased growth and uptake of glutaraldehyde during light periods?

I started dosing around 1.3 ppm in my tanks 2 days ago to take part in this experiment (even tanks with absolutely no algae are getting it to see if it increases plant growth).


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## hooha

well if you find any info/advice in the hobby cited in academic literature I'd love to see the articles! Most of the stuff seems to anecdotal, with the occasional "see my post 5 or 6 years back in (insert a internet forum here).


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## Freemann

Hi
From what I have read Seachem is the one that introduced the use of glutaraldehyde as a CO2 replacement and I think as an algae reducer in one of their pond products (not 100% sure on this one) if you just want some more info on glutaraldehyde from hobbyists, this guys from India have experimented extensively on it's use, you may check this here:
http://indianaquariumhobbyist.com/c...ile=viewtopic&t=2917&highlight=glutaraldehyde


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## epicfish

SeaChem uses a cyclic form of glutaraldehyde (polycycloglutaracetal) with various side chains...all proprietary information, of course. Their cyclic form plus stabilizing side chains helps to stabilize the compound and might help to reduce the toxic side effects. I believe it also helps to promote uptake by plants, or that's what SeaChem claims.


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## Fortuna Wolf

ok... glutaraldehyde can form bonds on either end (its a 5 carbon chain with aldehydes at the end), or you can think of it as 5 carbon chain with acetyls with R as H. 
The stuff you buy as a polymerizer for tanning, embalming, or as a sterilant is mostly unpolymerized so its still reactive and it will slowly self polymerize... forming cyclical chains with branching side groups of aldehyde. 
The stuff in Excel is just selfpolymerized glutaraldehyde so its less reactive/toxic, but its also a higher molecular weight. Here's the wiki on Aldol condensation: http://en.wikipedia.org/wiki/Aldol_condensation

A bit more digging around my textbooks. Glutaraldehyde is somewhat similar to some of the intermediate carbon chains in C4/CAM carbon fixation, but not so similar to those in C3. Now, there really won't be any CAM aquatic plants so don't worry about them. I wonder if C4 plants get more of a benefit than C3 plants.


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## dennis

No, in fact they get blasted by it. Elodea densa, riccia and valisneria sp., all species that prevently use bicarbonates for the water as a carbon source, are very sensitive to Excel and gluteraldehyde. I am not sure exactly how those plants compare or differ in respect to C3/4 and CAM physiology but there is something negative with plants that readily use bicarbonates.


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## Fortuna Wolf

Hummm, ok. I'm going to continue to try and figure out how the glutaraldehyde might help the reaction. 
Some articles I've been reading say that glutaraldehyde exists in a polymerized form in high concentrations (50%+), and separates to monomers in lower concentrations. Somehow I'm not believing them that much. It requires water to form an enolate ion from the aldehyde group to self polymerize.

This site http://www.worksafesask.ca/files/ccohs/cheminfo/cie4.html says:


> Stability:
> Normally stable, but can oxidize in air. Stability decreases as the pH and temperature increase.(1) Commercial solutions are usually stored at an acidic pH (about 3-4) to slow polymerization and then activated by raising the pH to a slightly alkaline state.
> 
> Hazardous Polymerization:
> Slowly polymerizes in presence of water and when heated.


and http://www.freepatentsonline.com/4859186.html


> In spite of the proven ability of glutaraldehyde to function as a neutral fixative, there are disadvantages and limitations which have prevented the widespread use of glutaraldehyde as a pulpotomy agent. The most serious of these limitations is a result of the chemical properties of glutaraldehyde. *In aqueous solution, glutaraldehyde is mildly acidic, relatively inert, and very stable. Elevation of the pH of an aqueous glutaraldehyde solution increases the microbicidal action of the glutaraldehyde (Stonehill, et al., supra).Unfortunately, at high pH, glutaraldehyde polymerizes, thereby losing that microbicidal activity.* A buffer can be used to maintain the pH of the solution at a mildly alkaline level, i.e., at near physiological pH, and sodium phosphate buffer has been used for that purpose, (Ranly, D. M. and E. P. Lazzari, "A biochemical study of two bifunctional reagents as alternatives to formocresol," 62 J. Dent. Res. 1054 (1983)). A sodium bicarbonate buffer can also be used for that purpose, however the results are less satisfactory because that buffer reacts too easily with the protons that are available in the solution to form carbon dioxide, decreasing buffering capability. However, even in a buffered, mildly alkaline solution, glutaraldehyde loses microbial activity eventually as a result of increased polymerization over time, thereby limiting the shelf life of the solution. Such solutions are also sensitive to temperature; exposure to heat increases polymerization such that aqueous glutaraldehyde solutions are routinely stored at cold temperature even for short periods of time.


So the conditions for self polymerization are increasing temperature and water or high pH. Basically, the carbonyl group (C=O bond) becomes an enol (C-OH bond, moving the double bond to another site), which then becomes an enolate ion (C-O- ion). The proton is donated either to water to form a hydronium ion or to a hydroxide ion to form water in solution. The enolate is the active site which will bond to another carbon chain (the oxygen from the enolate and hydrogen from the other molecule will pop off to form water).

Hmmm, so in some sense it does require water to depolymerize too. 
Anyhow, I bet that we can make our own polymerized glutaraldehyde by just heating an aqueous solution of glutaraldehyde or raising the pH with sodium bicarbonate. This should be somewhat less reactive in solution.


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## dennis

I'm not sure I'd want to cook the stuff. I think they even mention on the bottles to be careful of the fumes.

I bought some 25% BIO grade stuff for use in electron microscopy. Dilute it to a 10% solution and dose 1ml per 10liters. Seemed to do about the same as Excel but not worth the effort (same with Excel). IT was nice to beat back an algae issue as BBA is hard to get rid of physically. Yes, I fixed the problem but you still have to clean up the residue


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## Fortuna Wolf

I'm using it to try to get rid of some spirogea. I also have a tank... 5 really... from a bunch of cuttings from friends or the petstore that occasionally gets in a potted plant and then you never see that species again for months. So far 1 pot of marsilea crenata has covered half of a 125 gallon, and 1 pot of eleocharis has covered the other half. I want them to grow faster and fill the aquarium out so if it also does that it would be awesome. 

Well, I'm not suggesting cooking it, though raising the temp in the microwave in a sealed container isn't something to particularly fearful. Anyhow, I can buy 500ml @ 50% for $28 from alfa.com which'll make 10L of 2.5% excel flourish so for me its economical as well as purely interesting. 

A good amount of sodium bicarbonate or hydroxide should also raise the pH quite high and start the polymerization reaction. It'll probably be fully polymerized at equilibrium after a few days at room temp. The 3.4% stuff I bought has a mildly alkaline solution to "activate" it. It lasts 28 days before it drops to 1.5% activity (though the polymerized glutaraldehyde is still in it). So a very strong base should really make it take off.


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## LSD25

I was actually also looking for scientific literature on glutaraldehyde. The only thing I could find was on its toxicity on different organisms, such as Daphnia.

Its Sano LL, Krueger AM, Laundrum PF (2005). "Chronic toxicity of glutaraldehyde: differential sensitivity of three freshwater organisms, _Aquatic Toxicology _71,283-296.

I would love to read more about its capability to improve growth and its metabolism... Anyone out there? 

Cheers


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## Fortuna Wolf

LSD25, if you haven't found it already. Rename this from an mp3 to a pdf. http://www.aquaticplantcentral.com/forumapc/aquarium-pictures/showimage.php?i=4434&c=3
Its the paper.

In it it cites diffuculty hatching fish larvae and adult mortaility around 1.5-2.5 mg/L
The green algae they used in the study had a LD50 around 1 mg/L.
These are actually pretty close to the concentrations we use in the aquarium. 1mg/L ~ 1ppm (or nearly so, since the specific gravity is 1.06 g/ml).
We're dosing, at a single dose of excel, .625mg/L ~.625ppm. So a double dose would be 1.25ppm, toxic or lethal to most green algae. I think it would be wise to note that a quadruple dose is observed lethal for some fish and eggs. The water change dose of excel is recommended to be 3.125 ppm. 
However, within a period of 24 hours in these simple cultures (mostly organic free) there was an observed 75% reduction in glutaraldehyde. In an aquarium where you have plants, and lots and lots of organics, I would be inclined to expect a near 100% reduction in glutaraldehyde over 24 hours. So I would pick a toxicity threshhold and hammer things at that specific threshhold daily without worrying about accumulating it in the aquarium (though a day off for organisms to recover might be necessary).

Fluorish Excel is probably again, less biocidal which is why they can recommend a higher initial dose. Anyone using unpolymerized glutaraldehyde should use less. Based on that paper I'm going to recommend no more than 2 ppm or 3ml/4L of 2.5% glutaraldehyde (triple dose if we standardize a dose at 1ml/4L of 2.5%). 
-------------------
In other news, I procured a flask of 50% glutaraldehy from the EM lab. Does anyone want to help me fund an academic paper? I figure it'll take 2-3 months to set up the experiment and gather the data, and then 6-12 months to publish the paper after I submit it (lol). 
There are three things I want to study and can do with a few 10 gallon aquariums, some plant nutrient salts off the shelf, plants, and grow lights, and lots of sterile technique.

normal aquarium: 
This is just to publish in academic literature proof (or not) of whether or not glutaraldehyde can benefit a normal aquarium. Should also give data on whether or not it will kill algae and not plants (though I'm not in doubt of that, I've seen it with my own eyes). 
1 set of aquariums with goldfish, some ludwigia, eleocharis, other plants, sand, and every algae strain I can get my hands on. Set them up exactly the same, and then treat exactly the same and measure growth by number of leaves. 1 week after set up separate and begin glutaraldehyde treatment on half. Take measurements daily. 
2 weeks after treatments begin start adding high doses of fertilizers (would normally encourage algae growth), observe for a further 2 weeks. Tear down/give away aquariums.

Sterile plant culture: 
To make sure that the enhanced plant growth is not simply due to the removal of algae I'll grow a few cultures of aquarium plants in identical aquariums in sterile water. Air and water circulation will be provided from an airpump with a sterile filter on it. Water, nutrients, and glutaraldehyde will each be provided from preloaded and autoclaved syringes connected to a tube to the sealed aquarium. (or in the case of water, probably sterile water with an additional filter on a tube to the aquarium). Observations can again be made by counting leaves.

glutaraldehyde, or polycycloglutaracetyl?
Lol, I love that name seachem gave it to try not to give away what it was. If you go to seachem's website it has a graphic on how their chemical is similar to ribulose 1,5 bisphosphate (part of the photosynthesis carbon cycle). It shows RuBP, and next to it is a 5 chain carbon molecule, where every side chain is marked R1 through R5. Anyone who has taken O-chem should find this freaking hilarious. OMG INFORMATIVE. As I've said before, I think that seachem just uses polymerized glutaraldehyde. I'll polymerize some glutaraldehyde and then separate the tanks again, this time dosing one with unpolymerized GA, and the other with polymerized GA to see the differences. There's a chance that polymerized GA will have increased growth since the carbon fixation benefits are still there, but its decreased toxicity doesn't inhibit growth either.

Funding should be reasonable, in the range of a few hundred dollars. $10/tank, fish, plants, some murashige and skoog salts, borrowed GA from the EM lab, some fluorescent lights. Borrowed equipment... hehe. Time to complete the data taking? 1-2 months.

Worth trying? Fund my research!


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## LSD25

Fortuna Wolf said:


> LSD25, if you haven't found it already. Rename this from an mp3 to a pdf. http://www.aquaticplantcentral.com/forumapc/aquarium-pictures/showimage.php?i=4434&c=3
> Its the paper.


Sorry. The link doesnt work for me.

I cant fund your research, however, my knowledge in biochemistry might help.  I can review the experiment layout and may help otherwise as well.

I also had some other ideas, however, I dont have the place or lab available.

Cheers


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## Leonard

I'm using EasyLife EasyCarbo (but have been overdosing it fore a while now), it's almost the same thing as excel.

Some of my plants (maybe carbonate-plants) have just roten  for examlpe Rotala sp. "Green" and Ludwigia acurata, but I don't think they are bringing up carbonate, or?
And it have done sulphur in my sand, so my bottom is now destroyed and I've got GW.
But it have brought away other kinds of algea.

Do you think it works ok with snails and shrimps in ordinary doses? Or will the animals die?


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## Fortuna Wolf

I've been dosing at about 70ml/day of 2.5% GA in a 125 gallon tank and my shrimp are fine, but the water is cloudy. Trying to kill some spirogea - its definitely not growing but I don't know if its dying.


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## wfpearson

Any progress, results, updates on the glutaraldehyde polymerization? I'm certainly a novice so I'm confused people talk about raising the pH to a "high level" or a "mildly alkaline solution". These seem like relative terms to me. It it something that I could do in my kitchen with A&H baking soda in a pyrex dish? 

I'm going to ask my brother the chemist for some chemical support on this one, since he's always calling me for tech support.


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## hoppycalif

"2 weeks after treatments begin start adding high doses of fertilizers (would normally encourage algae growth), observe for a further 2 weeks. Tear down/give away aquariums."

I don't know where you stand with your experiment, but just adding high doses of nitrates, phosphates and traces won't encourage algae growth. If you want to make algae grow add a bit of ammonia to the water. Of course you would have to be very careful doing that, to avoid killing the livestock. 

What is the status of your experiment?


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## Fortuna Wolf

Experiment is currently nowhere, since I lack any funding. I was just "downsized" from my summer job (they quit serving lunch and I was the lunch server), so I'm scrambling to find student loans


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