Organic carbon dosing?

[Clay]

I was curious if anyone has worked with organic carbon dosing as a means of nitrate and phosphate removal in freshwater tanks? I know some people have some incredibly high nitrate levels, and I was interested in the results on a freshwater tank.

Granted, we freshwater people just do a water change, add some prime and move on. But that's not the question. The question is does it work?

For those who aren't aware or aren't familiar with the idea, basically (very basic) in the saltwater community, people have experimented (very successfully) with adding organic carbon sources to the tank in small doses. The vodka, vinegar, or sugar (organic carbon sources) rapidly feed bacteria forming long chains and rapidly bind/consume nitrates and phosphates. They are then removed by the skimmer. Skimmate goes from a light brown to a black and gooey consistency fairly quickly, however, nitrates end up being relatively low and maintainable without issues. They reduce fairly quickly as I understand, so a tank with high nitrates may find quick relief with a little vodka (not flavored).

What would happen with the long bacteria strings? They would die after consuming the food, but would regular dosing lead to a balance of nitrate consuming bacteria leading to a revolution of water change free tanks in the freshwater community? I dunno.

Who's brave enough to find out?

Or you can just tell me if it worked for you or if you know of any results of a similar experiment. Again, this isn't my thought or idea, I'm just posing a general question.

 

[Clay]

No thoughts on the subject?

 

[12 Volt Man]

the idea is that you are providing bacteria with a high BOD load in the form of the carbon source, which allows them to go crazy in terms of population and consumption.

however, in order to reduce the nitrates you need anaerobic bacteria which would only be found in deep sand beds in saltwater tanks in near anoxic conditions.

in a normal freshwater tank, conditions do not exist for such a population (except in extreme cases where your undergravel plate is full of crap and it goes septic etc) so it may serve as little use in a normal freshwater setup.

 

[Clay]

Interesting, but I don't think DSBs are a prerequisite for vodka dosing. Where would you think anaerobic conditions are coming from in the absence of a dsb?

 

[12 Volt Man]

hmmm.. in a saltwater tank without a deep sand bed, the only areas where you would get anaerobic conditions would be underneath the live rock. you would get dead spots that would create conditions for anaerobic bacteria. of course, these are the only types of bacteria that can reduce nitrates back to nitrites.

 

[Clay]

I dunno, I don't think it's an anaerobic function, tbh. The idea is that the bacteria consumes and binds it. There is even media for a high flow situation (media reactor). We're talking about people who have 30-50x turnover in their tanks, so there isn't a stagnant area in the tank.

Here:
http://www.reefcentral.com/forums/showthread.php?t=1694529

It's a long thread, but I think you'll find that these tanks are free of DSBs, anaerobic zones, etc. It's a function of the vodka (or pellets - solid vodka dosing)

 

[Zander_The_RBP]

I dunno, I don't think it's an anaerobic function, tbh. The idea is that the bacteria consumes and binds it. There is even media for a high flow situation (media reactor). We're talking about people who have 30-50x turnover in their tanks, so there isn't a stagnant area in the tank.

Here:
http://www.reefcentral.com/forums/showthread.php?t=1694529

It's a long thread, but I think you'll find that these tanks are free of DSBs, anaerobic zones, etc. It's a function of the vodka (or pellets - solid vodka dosing)

The thing your taking about seems to be the use of other bacteria that bind nitrates to sugars and the skimmer then removes them correct? Most freshwater tanks don't have a skimmer and theres really no practical way to get one to opperate properly on a freshwater tank. so it brings up the question of how to remove these complexes after their produced.



anaerobic respiration works in saltwater because live rock is incredibly porous and in the outer pores aerobic bacteria will grow consuming all the oxygen so as the water gets towards the center of the rock there is little or no oxygen left. Same principle applies in deep sand beds (in freshwater and saltwater) Is it possible to do in freshwater? Yes but you risk the production of hydrogen sulfide which reacts with water to produce sulfuric acid rapidly dropping the pH (saltwater has a ton more buffers in it so the pH is much more resistant to dropping).

The thing your taking about seems to be the use of other bacteria that bind nitrates to sugars and the skimmer then removes them correct? Most freshwater tanks don't have a skimmer and theres really no practical way to get one to opperate properly on a freshwater tank. So it brings up the question of how to remove these complexes after their produced.

 

[Danger_Chicken]

Saltwater people have a lot more chemistry to deal with than we do. But that does come with more ways to deal with it; unfortantly that chemistry is also why a lot of SW techniques wont work in fresh. Some can be modified to work; you could always setup a 20g with some convicts or jewels and give it a try. You might find a way to make it work.

 

[boldtogether]

Biological Oxygen Demand is a RESULT of high nitrate and phosfate in the water. As the bio activity increases(when you "feed" the bacteria) oxygen(DO_Disolved Oxygen) is decreased...killing your fish.
Biochemical Oxygen Demand(cBOD) is what you are then creating with the addition of "organic carbon", increasing biological activity to compensate, increasing BOD.
Just change your water.
Or, the nitrate reductor towers utilizing a reaction chamber, nitrate absorbing media and slow waterflow work. But you run the risk and hassle of removing this nitrate absorbing sulpher media from the water column. There is the sump filters that have a nitrate removing chamber that is essentially a chamber that fosters anaerobic conditions and these anaerobic bacteria consume the nitrate and expell nitrogen.
About the only way to remove nitrate without creating huge problems is weekly water changes of more that 50%.
I dont think a "water change free" tank is possible.

 

[12 Volt Man]

one thing that we should clarify is that BOD is not a pollutant but rather an index used to measure the strength of pollution.

in a freshwater tank, the nitrate levels would be the pollutant, and the BOD test would be used to measure the strength of the pollutant levels via the metabolism of bacteria and consequent oxygen depletion (which is what can be quantitatively measured usually using the Winkler method).