Vodka or sugar + fishtank = ?

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luohanfan

Candiru
MFK Member
Dec 22, 2009
463
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Australia
has anyone tried either of these as a source of DOC to promote anaerobic bacteria?
If so, what were your results?
I plan on trying this to promote small blooms which inturn will consume nitrates, the be taken from my system using a skimmer..
The idea is to control nitrates and keep water conditions perfect without doing so many water changes..
Your thoughts?
 
this concept is completely foreign to me, but im interested. Can you explain this theory further?
 
denitrifying bacteria are heterotrophic. They “eat” organic carbon and “breath” NO3-. Specifically they consume dissolved organic carbon (DOC). The size and activity level of your denitrifier population is limited by how much DOC and NO3- you have floating around in your water. In the real world, DOC will be the limiting factor in Tank because there is always plenty of NO3- around. so you could dose your tanks with sugar, ethanol, or other soluble organic substances.
 
Anerobic bacteria excrete an assortment of toxic gasses...most of which are sulfide based. I go to great lengths to keep them out of my tank.

Denitrifying bacteria do NOT use DOC's to oxidize nitrate. DOC= Dissolved organic carbon... carbon, its an element on the periodic table that is distinctively missing from the formulas for ammonia (NH4) nitrite (No2-) and nitrate (No3-). The most common reaction for denitrification turns nitrate into Nitrogen gas and water. No carbon involved. The 10 spare electrons in the formula typically come from organic matter (carbon based substances) that are getting reduced. Notice I said reduced, not removed. Yes these bacteria are mostly heterotrophic, but their wastes are still carbon based and thus still DOC's, carbon dioxide is the most common one.

2NO3- + 10e- + 12H+ → N2 + 6H2O


A major flaw in your theory is that these things require anerobic conditions. Your water has DO in it. So you have to get these little bacteria guys water containing nitrates sufficiently to keep them alive and denitrifying with out getting them water that contains oxygen. Good luck with that part.

Futher adding to the troubles is the problem that DOC's that build up in your tank are toxic to the fish, shutting down metabolic pathways. So even if this worked (it won't btw) you would rid your tank of excess nitrates but not of excess DOC, and you just added more DOC to your tank in the form of Vodka (a fantastic preservative for all the fish you are about to kill too!!!) DOC levels are not readily tested for in home aquaria as the tests for them are complex, expensive and of poor accuracy. The best way to test for them is to measure the nitrates and know that if the nitrates are high, so are your DOC's.


Live plants btw do a great job of using up nitrates (but not DOC's) and can lower your levels for you. Even stuffing a spider plant "spider" into the top of an HOB filter will help lower nitrates, but you would still need to lower the level so f DOC's with a water change. Or you could..... CHANGE THE WATER IN YOUR TANK!

If you don't want to change the water in your tank, keep pet rocks. Its part of owning fish.
 
hahaha.. i don't mind changing my water..
But wouldn't it be worth knowing the exact effect this treatment has in case of emergency?
This isn't just a theory of mine.
It has been used for over 15 years oversea's with great results.
I don't need to create anaerobic conditions in my tank as i will be skimming the bacteria out that have just "eaten" the DOC and Nitrates..
The bacteria Eat the DOC right? so i wont get a build up..

P.s.. I'm just asking as i want to learn, so if you know more about this, just tell me.. im quite willing to listen :)
 
Yes they eat DOC. But they also excrete DOC. (In hindsite, the DOC excreted is probably CO2 which is going to get released harmlessly into the environment, I need to look into that.)

Ok, now you are making me think... I need more coffee.


Skimmers on fresh water don't generally work as the over all viscosity (I hope that is the right word) of the water is so low that the bubbles don't form... how are you getting past that?

The denitrifying bacteria don't live in oxygenated environments. They need DO to be lower than 0.2mg/L. Your fish need DO to be a lot closer to 6mg/L an entire order of magnitude larger and then some.

I don't understand this sentence..."I don't need to create anaerobic conditions in my tank as i will be skimming the bacteria out that have just "eaten" the DOC and Nitrates.." The bacteria won't live in your tank? At heterotrophs they get the oxygen (still required for respiration last I checked) from the nitrate... thus turning it into N2... if you are removing them from the tank that solves the issue of excrement, but not the issue of oxygen preventing their very presence.
 
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