dosing vodka to bring down N and P

[ATJ]

Originally posted by Randy Holmes-Farley
When I dosed sugar once, many of my corals turned brown. Probably zooxanthallae growing much faster.

Zooxanthellae produce sugar via photosynthesis. I don't see why increasing the amount of sugar in the water would make them grow any faster.

[Randy Holmes-Farley]

oxanthellae produce sugar via photosynthesis. I don't see why increasing the amount of sugar in the water would make them grow any faster.

Because they have more to eat and so are not limited by photosynthesis?

I agree that there may be other explanations for the browning as well.

[crlkeep]

Zooxanthellae produce sugar via photosynthesis. I don't see why increasing the amount of sugar in the water would make them grow any faster.

I believe that the sugars produced by zooxanthellae are a little different than the sugars used to produce this "bacterial bloom". Assuming it was something like processed white table sugar.

IIRC the slime coating on these corals may be used to trap bacteria and other matter for the corals to digest as food. Which would mean extra nutrients inside to coral for feeding the Zooxanthaellae.

Randy,
When you added sugar, where you referring to regular Table sugar?

I think Dr. Ron had an interesting point on this when he said these tanks may be anorexic. Assuming he meant "starved".

I think that I will stick to Caulerpa to remove these nutrients.

[ATJ]

Originally posted by crlkeep
I believe that the sugars produced by zooxanthellae are a little different than the sugars used to produce this "bacterial bloom". Assuming it was something like processed white table sugar.

Sugar is sugar to these organisms no matter whether it is sucrose, glucose or something more complex. They are just different forms of carbohydrates - they all provide energy through respiration.

[Randy Holmes-Farley]

I believe that it was table sugar that I used. I'll search on carbohydrates and zoox tomorrow and see what turns up.

[crlkeep]

Sugar is sugar to these organisms no matter whether it is sucrose, glucose or something more complex. They are just different forms of carbohydrates - they all provide energy through respiration.

I did not know that. Learn something new everyday.

Maybe the corals are trying the Atkin's diet...

[ButterfyBoy]

Zooxanthellae produce sugar via photosynthesis. I don't see why increasing the amount of sugar in the water would make them grow any faster.

Except that you are assuming that they can only utilize sugar produced through photosynthesis. If its avaliable externally as well, isn't it likely that they will use as much of it as possible in addition to what they directly produce? I think it's not unlikely that they have multiple vectors for meeting their sugar demands.
Alternatively, could it also be that the coral polyp is utilizing the sugar, in turn resulting in an increased CO2 production which is thus indirectly stimulating the zooxanthellae?

[ATJ]

Originally posted by ButterfyBoy
Except that you are assuming that they can only utilize sugar produced through photosynthesis. If its avaliable externally as well, isn't it likely that they will use as much of it as possible in addition to what they directly produce? I think it's not unlikely that they have multiple vectors for meeting their sugar demands.
Alternatively, could it also be that the coral polyp is utilizing the sugar, in turn resulting in an increased CO2 production which is thus indirectly stimulating the zooxanthellae?

I doubt either of these would be the case, but the latter may be more possible, in my opinion.

Under normal conditions, the zooxanthellae living within the coral tissues produce sugars in excess to their own needs and pass these on to the coral host (in the form of glycerol, I believe). In some species almost half of the carbohydrates produce by photosynthesis is passed on to the host animal. i.e. they are producing almost twice the carbohydrates that they need.

If they are already producing more sugar than they need, why would they utilize the added sugar? Why wouldn't that be utilizing the sugars that are being passed to the host?

I agree that the coral itself may be able to utilise the sugar, but why would this cause a significant increase in respiration? CO₂ is only going to be produced when the carbohydrates are "burnt" for energy. Why does the coral use more energy?

Additionally, the photosynthetic rate of most corals in captivity would be limited by irradiance levels more that CO₂ levels. If CO₂ levels were limiting, you might see an increase in the photosynthetic rate, but I believe most tanks are going to have higher CO₂ levels than reef seawater, especially if a calcium carbonate reactor is in use.

[Randy Holmes-Farley]

I agree that under normal circumstances, sugars of various sorts are passed from the zoox to the host coral.

However, glucose in the water can apparently be taken up by both zoox and by corals:

Glucose and glycerol uptake by isolated zooxanthellae from Cassiopea xamachana: transport mechanisms and regulation by host homogenate fractions. McDermott, A. Macon; Blanquet, R. S. Dep. Biol., Georgetown Univ., Washington, DC, USA. Marine Biology (Berlin, Germany) (1991), 108(1), 129-36.

Abstract

The mechanisms were investigated by which glycerol and glucose enter freshly isolated zooxanthellae (FIZ), Symbiodinium microadriaticum, of the mangrove jellyfish, Cassiopea xamachana, and the specific sites of host factor interaction. Glucose entry into FIZ is accomplished by a Na+-dependent symport system driven by an electrochem. gradient generated via a Na+-K+ ATPase. Inhibition of glucose uptake by a low-mol.-wt. fraction of host homogenates [mol. wt. <2 kilodaltons (kD)] occurs through the interaction of a putative host factor with the carrier protein and not the ATPase. Glycerol entry is apparently accomplished by simple or facilitated diffusion and is not affected by host homogenate fractions.



Uptake of organic material by aquatic invertebrates. I. Uptake of glucose by the solitary coral, Fungia scutaria. Stephens, Grover C. Univ. of Minnesota, Minneapolis, Biological Bulletin (Woods Hole, MA, United States) (1962), 123 648-59.

Abstract

The hypothesis that some marine animals are capable of removing small org. mols. of biol. significance from very dil. soln. was supported by the complete recovery of C14 by F. scutaria kept in 0.5-10 mg./l. glucose-C14 soln. Uptake did not occur through the mouth of the organism or by adsorption on mucus and was little affected by temp. Lysine, aspartic acid, tyrosine, glycine, and lactate were similarly taken up from dil. solns., but sucrose, galactose, ribose, and arabinose were not taken up from any concn. Uptake of glycine was not affected by phlorizin. Glucose uptake was inhibited by phlorizin but not by 2,4-dinitrophenol.

[crlkeep]

Interesting.....

How does Table Sugar add up? I am not familiar with its classification as a sugar, aside from it's being sweet...

[Randy Holmes-Farley]

Table sugar is sucrose, which is a disaccharide composed of one glucose attached to one fructose. I do not know what corals or zoox might do with sucrose itself (except as mentioned in teh second reference), nor whether when adding sucrose to a reef aquarium, you get any free glucose or fructose (or any other metabolic byproducts) in solution.

[crlkeep]

Any idea on whether bacteria may break down sucrose into one or the other?

Or if the bacteria may take up sucrose and be captured by the coral then broken down in it's gut to release either glucose or fructose?

[Randy Holmes-Farley]

Bacteria certainly break it down rapidly. The question is whether they consume all that they break down or not.

A bacterial bloom that could be consumed by corals is another possibility for what the sugar might do.

[crlkeep]

I have to admit that when I first started reading this thread I thought it was a joke...

Now it seems to have some very interesting merits...

It will be very interesting to see what information may be found from topics like this.

[ATJ]

Originally posted by Randy Holmes-Farley
Glucose and glycerol uptake by isolated zooxanthellae from Cassiopea xamachana: transport mechanisms and regulation by host homogenate fractions. McDermott, A. Macon; Blanquet, R. S. Dep. Biol., Georgetown Univ., Washington, DC, USA. Marine Biology (Berlin, Germany) (1991), 108(1), 129-36.

Abstract

The mechanisms were investigated by which glycerol and glucose enter freshly isolated zooxanthellae (FIZ), Symbiodinium microadriaticum, of the mangrove jellyfish, Cassiopea xamachana, and the specific sites of host factor interaction. Glucose entry into FIZ is accomplished by a Na+-dependent symport system driven by an electrochem. gradient generated via a Na+-K+ ATPase. Inhibition of glucose uptake by a low-mol.-wt. fraction of host homogenates [mol. wt. <2 kilodaltons (kD)] occurs through the interaction of a putative host factor with the carrier protein and not the ATPase. Glycerol entry is apparently accomplished by simple or facilitated diffusion and is not affected by host homogenate fractions.

While this shows that zooxanthellae can take up glycerol, I still don't believe this is going to happen in healthy corals. Perhaps if light was severly limiting, extra carbohydrates in the water could be utilised by the zooxanthellae as a substitute for photosynthesis. It may even occur in "healthy" corals where the products of photosynthesis can be distributed to from zooxanthellae in lighted areas of the corals to those in shaded areas - although, I'm not sure what the long term value for this would be.

Uptake of organic material by aquatic invertebrates. I. Uptake of glucose by the solitary coral, Fungia scutaria. Stephens, Grover C. Univ. of Minnesota, Minneapolis, Biological Bulletin (Woods Hole, MA, United States) (1962), 123 648-59.

Abstract

The hypothesis that some marine animals are capable of removing small org. mols. of biol. significance from very dil. soln. was supported by the complete recovery of C14 by F. scutaria kept in 0.5-10 mg./l. glucose-C14 soln. Uptake did not occur through the mouth of the organism or by adsorption on mucus and was little affected by temp. Lysine, aspartic acid, tyrosine, glycine, and lactate were similarly taken up from dil. solns., but sucrose, galactose, ribose, and arabinose were not taken up from any concn. Uptake of glycine was not affected by phlorizin. Glucose uptake was inhibited by phlorizin but not by 2,4-dinitrophenol.

We already know that corals can absorb the carbohydrates released from the zooxanthellae, so I guess this is not so surprising.

Here is an interesting study into the use of the carbohydrates passed from the zooxanthellae to their coral hosts:
Coral uses slimy mucus to donate food.

[crlkeep]

That was an interesting article. I also enjoyed the article that followed on the cyclone causing the reef to avoid a bleaching event.

Nature sure does try hard to counter the affects of man...

[ButterfyBoy]

I do see where ATJ is coming from with that. Out of curiousity, is there any substantial evidence that this reported apparent "browning" of coral tissues following the addition of glucose is actually due to the zooxanthellae? Or could we be seeing a proliferation of other commensal microorganisms, algae or bacteria or such? I suppose what I'm asking is, do we know of any other organisms that live within coral tissue, besides zooxanthellae, that might multiply in the presence of additional sugars and thus cause the discoloration that is being attributed to zooxanthellae?

[Randy Holmes-Farley]

do we know of any other organisms that live within coral tissue, besides zooxanthellae, that might multiply in the presence of additional sugars and thus cause the discoloration that is being attributed to zooxanthellae?

I don't know. I thought of zoox because browning due to incresed zoox appears to happen in other situations, like low light. But there could be many other explanations, including the corals themselves making more pigment.

[wasp]

Around 3 weeks ago I started dosing 2 mls vodka daily into my total of 75 g system. The water went really clear and the algae whitened, but after a few days the mushrooms shrivelled to less than 1/2 normal size. I therefore reduced the dose to 1 ml per day.
The mushrooms have slowly recovered, but the algae has come back also. Therefore, 2 days ago I increased the dose back to 2 mls daily, the algae has again whitened, but this time the mushrooms are very slightly shrivelled, but not very much, they must be adapting.
Basically I am trying to find at what point is the optimum dose. I will post again in another few weeks.

[Poriferaphile]

This topic caught my interest, as I had several years ago built a large coil denitrator that used methanol as its fuel source. (It worked ok but was a pain in the butt to run, and was gladly discarded after I discovered deep-sand denitrification.) I used methanol because it was the standard carbon source for municipal-scale denitrification and a lot of science had been done on the method. I suspect that this is where these German aquarists got the idea that ethanol would be a similarly good food for their bacteria, as well as being less toxic than methanol.

In any case, as with the sugar-dosing experiments, this is tricky stuff. In particular, who knows how it might be metabolized in a particular system? There are a lot of different end-products for ethanol metabolism - typically acetate, but it is possible that some of the weird results people found were due to other end-products. Most interesting to me is ethylene, a gas long known as a stimulant to fruit ripening, but scientists are learning how it has many actions as a hormone signalling metabolic processes in plants, and more recently in some higher animals. Here are a few links that may be of interest:

http://www.uea.ac.uk/env/marinegas/r...h/ethene.shtml
http://www.plantcell.org/cgi/reprint...ppl_1/S131.pdf
http://www.biomedcentral.com/1471-2121/2/7

How can ethanol get converted to ethylene in the aquarium? There are various ways: one might be reaction catalyzed by UV light - present in significant quantity with MH lighting. Another might be a natural process by a plant - let’s say a particular macroalga uses ethylene in signalling sexual reproduction. It might produce a significant amount which would in the ocean be quickly diluted, but in the aquarium be concentrated. A third possible method is catalysis by substrates or filtering material - one way ethylene is manufactured is by using zeolite (a porous aluminosilicate mineral). Different types of zeolite are made for aquarium use to remove ammonia, phosphates, and heavy metals. (The Zeovit system mentioned in this thread uses zeolites.) It’s possible that some of these filtering materials are the right type to convert ethanol to ethylene. It’s even possible that natural coralline materials might have a zeolite-type structure and function in the same way.

I know this is so much speculation on my part, but it seems plausible, and could explain why different people have had widely divergent experiences dosing ethanol.

-Rick Andrews

[wasp]

That's very interesting, Poriferaphile, although a lot of that stuff was beyond my science education.
I'm really trying to understand the science behind vodka dosing, because of the dramatic improvement it has made to my tank. Some people I know have started using the zeovit system, but I do wonder if they are spending a ton of money to achieve the same thing I am getting with just a very small dosing of vodka.
I just feel like I am playing with the unknown though, and would like to have a better understanding of what is actually happening in the tank.
I suspect that because nobody is going to make a whole lot of money from vodka dosing, there is no incentive to do any exhaustive research on it.

[Randy Holmes-Farley]

The function of organic molecules in marine aquaria and in natural seawater is a virtually wide open field. I expect there are lots of good things and lots of bad things happening because of the levels of particular organic compounds in aquaria, although most folks usually only think about toxins.

Ethylene could certainly be an interesting player. I don't have any reason to believe that it is naturally produced from ethanol, and in fact, ethanol might even inhibit natural biosynthesis. Nevertheless, it is an ineresting hypothesis.

Here's a paper showing that ethanol inhibits ethylene formation in tomatos (my bolding):


Role of alcohol dehydrogenase on ripening of ethanol-treated tomato and kiwifruit. Massantini, R.; Gobattoni, E.; Botondi, R.; Mencarelli, F. Istituto di Technologie Agroalimentari Universita' degli Studi della Tuscia, Viterbo, Italy. Acta Horticulturae (1995), 379(International Symposium on the Quality of Fruit and Vegetables: The Influence of Pre- and Post-Harvest Factors and Technology, 1993), 297-304.

Abstract

Ethanol vapor treatments for 8 h of tomato fruit disks stimulated greatly the ADH (alc. dehydrogenase) activity and inhibited ethylene biosynthesis. When 10 mM 4-methylpyrazole (4-MP), an inhibitor of ADH, was applied, ADH activity was halved in ethanol-treated disks and completely inhibited in water-treated tissues, and ethylene formation was also inhibited. 5 MM AVG (aminoethoxyvinylglycine) reduced ethylene evolution but did not affect ADH activity. In kiwifruit disks, ADH was only detectable after ethanol treatments and its activity was inhibited by 4-MP and AVG. ACC (1-aminocyclopropane-1-carboxylic acid) and ethephon stimulated ethylene but not ADH activity. Role and interation of ADH with ethylene are discussed.


Here's an article on mangos:

Acetaldehyde inhibition of ethylene biosynthesis in mango fruit. Burdon, Jeremy; Dori, Sasson; Marinansky, Rosita; Pesis, Edna. Volcani Centre, Agriculture Research Organisation, Bet Dagan, Israel. Postharvest Biology and Technology (1996), 8(2), 153-161.

Abstract

Mango fruit ripening is accompanied by increased ethylene prodn. which coordinates the ripening process. Ethylene prodn. in other fruit was inhibited by acetaldehyde and ethanol. In unripe mango fruit the ethylene prodn. is very low (<1 nL g-1 h-1) and treatments with acetaldehyde and ethanol had concn.-dependent effects on ethylene prodn. The application of 1-aminocyclopropane-1-carboxylic acid (ACC) to acetaldehyde or ethanol treated fruit disks showed acetaldehyde to be capable of completely eliminating increased ACC oxidase activity, whereas ethanol did not. Thus, acetaldehyde is capable of inhibiting the activity of ACC oxidase directly, or alternatively of preventing the increase in the enzyme, thereby providing a possible mechanism for retarding fruit ripening.

It also inhibits it in carnations:

Influence of ethanol on ethylene biosynthesis and flower senescence of cut carnation. Heins, R. D.; Blakely, N. Dep. Hortic., Michigan State Univ., East Lansing, MI, USA. Scientia Horticulturae (Amsterdam, Netherlands) (1980), 13(4), 361-9.

Abstract

Ethanol [64-17-5] (2%) in the holding-soln. inhibited climacteric C2H4 [74-85-1] biosynthesis and decreased the respiration rate 60% during a 7-day period in cut carnation flowers. Conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) [22059-21-8] to C2H4 was inhibited by adding ethanol to the holding-soln., with a simultaneous inhibition of ACC-induced senescence in carnation flowers. Ethanol was the most effective alc. in delaying carnation flower senescence of the tested series of C1-C4 alcs. Ovary development was also inhibited in cornation flowers by ethanol. The senescence of Easter lily flowers and tulip flowers was not delayed by ethanol.

[Poriferaphile]

Originally posted by wasp
... I'm really trying to understand the science behind vodka dosing, because of the dramatic improvement it has made to my tank.
... I just feel like I am playing with the unknown though

wasp,
The basic science is fairly straightforward in that the vodka works by feeding the denitrifying bacteria which reduces NO3 and PO4. However, I do think that you are taking a significant risk because of the other points I make, and because of the basic fact that you are introducing bioload in order to control bioload. It may work in the short term but IMHO does not seem to be a wise strategy. That said, I could be wrong - if you’re very careful, it could continue to work for you.

[Poriferaphile]

Originally posted by Randy Holmes-Farley
The function of organic molecules in marine aquaria and in natural seawater is a virtually wide open field. I expect there are lots of good things and lots of bad things happening because of the levels of particular organic compounds in aquaria, although most folks usually only think about toxins.

Randy, we agree so far.

Ethylene could certainly be an interesting player. I don't have any reason to believe that it is naturally produced from ethanol...

Here we part company. All three of my quoted articles mention that ethylene is produced photochemically from dissolved organic carbon, and I believe that ethanol qualifies as DOC. Also, as I mentioned, zeolite catalysis is a well-established method of ethylene synthesis, and zeolites are widely used in aquaria.

ethanol might even inhibit natural biosynthesis

Yes, and the articles you excerpt support that, but I did not try to make the argument that our plants were using the ethanol to make ethylene, only that plants do make ethylene and perhaps in quantities that would have a significant impact on a small closed system. Nevertheless, the articles you posted could hypothetically support my argument - if the ethanol acts like a finger in a dike to temporarily hold back the ethylene, then the water on the other side of the dike continues to build up, and when the finger is removed, the pressure will be that much greater.

My main points are these:
1. Ethylene is a powerful hormone controlling life cycle and gene expression in plants and animals, and we would be wise to learn more about it.
2. Natural processes in aquaria can produce ethylene in quantities that may affect overall aquarium health, and adding ethanol can be a significant source of that ethylene.
3. High variability may be at play in the system - if we decide PO4 is too high and add zeolite, change the lighting, a plant becomes mature, etc.
4. It is important to be informed about the ways in which we may be putting our treasured work at risk. In trying to make things better, we would do well not to take undue risk.

-Rick Andrews

[571958]

Hi Rick,

do you implied that both Vodka dosing and Zeovit is a DOC agent?

Max