question about vodka dosing

[sergifed91]

I started dosing vodka on 11/1/2018. although I don't dose very much. I started at .2 ml and up to .4 and in a day or 2 I will be dosing .9 for a week. but my question is since I started dosing I have started to notice small bubble coming from rocks that have been in my tank since april of this year. whats going on? is it still curing or is it the bacteria that converts nitrate to nitrogen?

 

[redfishbluefish]

Bacteria that converts nitrate to nitrogen are anaerobic bacteria (no oxygen).

What carbon dosing does....in your case, vodka...is to "feed" bacteria and cause them to grow and multiply. In the process of growing and multiplying, they are consuming nitrates and phosphates in their growing cells. Your skimmer now sucks this bacteria out of your tank, "exporting" the nitrates and phosphates.

 

[sergifed91]

Bacteria that converts nitrate to nitrogen are anaerobic bacteria (no oxygen).

What carbon dosing does....in your case, vodka...is to "feed" bacteria and cause them to grow and multiply. In the process of growing and multiplying, they are consuming nitrates and phosphates in their growing cells. Your skimmer now sucks this bacteria out of your tank, "exporting" the nitrates and phosphates.

I thought so. I do know that since I started dosing vodka my skimmer is a work horse. I have been emptying it every day since I started dosing vodka. so this is good news. I have been battling high nitrates and phosphates for a while. so when I test it tomorrow night I will also go to the LFS to verify my results with them.

 

[Dan_P]

I started dosing vodka on 11/1/2018. although I don't dose very much. I started at .2 ml and up to .4 and in a day or 2 I will be dosing .9 for a week. but my question is since I started dosing I have started to notice small bubble coming from rocks that have been in my tank since april of this year. whats going on? is it still curing or is it the bacteria that converts nitrate to nitrogen?

One story is that nitrate is converted to nitrogen gas as a result of dosing. Another idea is that bacteria are using nitrate as a precursor to ammonia and biomass formation because of dosing. Maybe both.

Seeing nitrogen bubbles when dosing so little carbon would be a lucky observation.

Are the doses you quote per gallon or the entire amount per day?

 

[sergifed91]

One story is that nitrate is converted to nitrogen gas as a result of dosing. Another idea is that bacteria are using nitrate as a precursor to ammonia and biomass formation because of dosing. Maybe both.

Seeing nitrogen bubbles when dosing so little carbon would be a lucky observation.

Are the doses you quote per gallon or the entire amount per day?

the entire day.

 

[redfishbluefish]

................ I have been battling high nitrates and phosphates for a while. so when I test it tomorrow night I will also go to the LFS to verify my results with them.

Don't expect quick results....it might take a couple weeks (months) to start to see your numbers go down.

 

[Dan_P]

Here is another story based on just a few small scale acetate dosing experiments I conducted. I say “story” so as not to imply scientfic fact.

The observation is that a lot more acetate is consumed than is needed to consume the nitrate, assuming nitrate is being converted to nitrogen gas. Also nitrate reduction seems greatest when oxygen concentration declines.

If the aquarium situation is similar to my small scale experiments, much carbon is going to be consumed with little nitrate reduction. It might be that the carbon consumption by aerobic bacteria might actually be lowering the available oxygen in the vicinity of the nitrate reducing bacteria. Until the oxgen is lowered enough, nitrate reduction does not occur at an appreciable rate. More added carbon, means more oxygen depletion and finally, at some point more ntrate reduction to nitrogen gas. Because oxygen is being constantly replenished in the aquarium, the rate of depletion has to exceed that replenishment rate before the local concentration starts to decline. The idea of increasing the dose over time may be an empirical approach to finding the sweet spot between sufficient of oxygen depletion in the locale of nitrate reduction but not enough to create a visible bacterial bloom. So, that’s the story. Up the dose more aggressively might be your answer.

 

[redfishbluefish]

Again, unless you have anaerobic areas in you DT/Sump, you're not going to get the nitrate to nitrogen conversion....and not the volume needed to reduce nitrate (phosphate) levels to all the food and poop added to your tank. That is, unless you add anaerobic areas to do this conversion, your tank/sump can't keep up to the amount of nitrates and phosphates added to your tank.

Now you're observation with acetate is spot on. If we go off Redfield ratios, the carbon: nitrate: phosphorus ratio is 106:16:1. So a whole bunch of carbon (vodka), a skoch of nitrate and a pinch of phosphorus. So yes, carbon is need in the biggest ratio when dosing. But also note, you do need all three for this to work. If you don't have any one of the components, it doesn't work (i.e. bacteria doesn't grow and multiply). Again, you're growing bacteria just to simply remove it by your skimmer. We're not looking at the bacteria (anaerobic) that converts nitrate to nitrogen....a minor component (unless you're doing something like Natureef).