Carbon dosing: how long to see results in my nitrate and phosphate

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Hal3134

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Tank is about 300g including sump. Nitrate is 50-100 ppm and phosphate is 1.0 ppm. Tank is about 18 months old and I’m just seeing coralline algae start to grow in little patches all over the tank.

Per Randy’s article I just completed day three of dosing 1.2 ml. The next three days will be 2.4 ml. Given the size of my tank, can I jump it up a little faster? And how long before I start to see my test levels come down? My skimmer is rated for 350-700 g tank (light bioload vs heavy bioload).
 
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Randy Holmes-Farley

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Mine never seemed to change much, msybe because I never collected sediment from the dump and elsewhere.

But it can take a couple of weeks from what folks report, especially if you start at a low dose.

Nitrate is the thing to key in on. Phosphate will change more slowly, if at all.
 

motortrendz

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Took about 6 weeks in my system before I started to notice it coming down. It didnt have any noticable effect on phosphates. As the nitrates start to come down I would run gfo or lanthanum to start removing the phosphates slowly while trying to keep a balance between the 2.
 

duffer

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It takes a while and I would not do anything different than the chart.. I can tell you carbon dosing will lower nitrates and you will see phosphates come down a little but it won’t come down a lot with carbon dosing
 
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Hal3134

Hal3134

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I’m dosing Vibrant weekly right now, but will likely change to every other week very soon. Can i speed up the reduction in nitrates and phosphates by also dosing Prodibio?
 

Dan_P

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Tank is about 300g including sump. Nitrate is 50-100 ppm and phosphate is 1.0 ppm. Tank is about 18 months old and I’m just seeing coralline algae start to grow in little patches all over the tank.

Per Randy’s article I just completed day three of dosing 1.2 ml. The next three days will be 2.4 ml. Given the size of my tank, can I jump it up a little faster? And how long before I start to see my test levels come down? My skimmer is rated for 350-700 g tank (light bioload vs heavy bioload).
What are you dosing?

The dosing tables on the internet and in all the articles on carbon dosing were scaled up incorrectly from the 25 gallon scale. If you are following those for a 300 gallon system you may never reach a dose sufficiently large to see a reduction in nitrate. Also, the increase in dose is also overly cautious.

As for phosphate reduction, deal the nitrate first. The bacteria population that will eventually increase and remove the nitrate will need phosphate for vigorous growth. Don’t starve them. When you reach the desired nitrate level, reduce the phosphate level as suggested with GFO or lanthanum.
 

ScottR

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I saw zero change during carbon dosing. Nothing. But I did get cyano. And then dinos. And then I wish I never had carbon dosed. I dosed for roughly 6 months before stopping after cyano.
 

Pedoconfuego

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I am dosing roughly 8 ounces of vinegar a day in my 100 gallon tank but have been dosing for a long time. It took a while to get up to this point. Once I had dosed for a few weeks I could up the dose a little more each week. You just don’t want to up the dose to much in the beginning because of bacteria blooms. I also agree starting that low seems like it would take forever to reduce nutrients in that size system.
The chart most go by says for a 300 gallon tank to do this...
First 3 days dose 10 ml
Next 3 days dose 20 ml
Then every week after this first week add 4 or 5 ml to the dose. After a couple months I could go quicker than that but wouldn’t suggest it unless you have dosed carbon before.
 

NanoDJS

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I am thinking it will take 2 months to stabilize slow and steady like that, I just had a similar situation , 3 po 45 no and got it down to .5 po / 10 no in around a week using super aggressive methods I would not suggest to anybody to use, I have had to do this many times before and have a system. Unless you have done it before and have the whole week to babysit the system the best methodology is what Randy and others prescribed , its a slow process but you will be rewarded with that size tank especially , it will also get you more intimate with the nute cycle and its impact on your own system ( seeing the changes ) slowly , have patience and keep up the good fight you will win !!!! Keep an eye on your P it will most likey deplete before you N being at the ratio you say. try to keep it up at the 1 its at now until ou get down to like 20 N or you could have some other issues.
 

Randy Holmes-Farley

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I saw zero change during carbon dosing. Nothing. But I did get cyano. And then dinos. And then I wish I never had carbon dosed. I dosed for roughly 6 months before stopping after cyano.
That can happen. Cyano likes organic carbon. I think the trick is to either have more of a different type of bacteria to outcompete the cyano for the organic, or use an organic that the cyano you have doesn’t like.

when I first started organic carbon dosing, I used vodka. That seemed to encourage my cyano. I switched to vinegar and that no longer happened, so I stuck with vinegar.
 
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ScottR

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That can happen. Cyano likes organic carbon. I think the trick is to either have more of a different type of bacteria to outcompete the cyano for the organic, or use an organic that the cyano you have doesn’t like.

when I first started organic carbon dosing, I used vodka. That seemed to encourage my cyano. I switched to vinegar and that no longer happened, so I stuck with vinegar.
I’m interested in trying vinegar. I’m just curious if it’ll make any impact that vodka didn’t. The blind spot for me in this hobby is what happens to nitrates after they get converted from NO2. I think they can turn into nitrogen gas and get expelled from the water? As far as I know, carbon dosing won’t do that. Any idea?
 

Randy Holmes-Farley

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I’m interested in trying vinegar. I’m just curious if it’ll make any impact that vodka didn’t. The blind spot for me in this hobby is what happens to nitrates after they get converted from NO2. I think they can turn into nitrogen gas and get expelled from the water? As far as I know, carbon dosing won’t do that. Any idea?
Carbon dosing can drive growth and incorporation of N from nitrate into tissue, and formation of N2 by denitrification. An organic compound of some sort is required for denitrification.
 

Randy Holmes-Farley

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This has more:


From it:


9. Organic Carbon Dosing

Organic carbon dosing involves adding a soluble organic compound to the aquarium which spurs bacterial growth. Typical organics used can be ethanol (as vodka), acetic acid (as vinegar), calcium acetate (as lime saturated vinegar), sugar (sucrose) and many others. Vodka and vinegar are by far the most popular. I use vinegar.

These organic molecules can be used by many organisms, including corals, but the main intent is to drive bacterial growth. To grow, the bacteria need a source of nitrogen and a source of phosphate, and a large portion of these they remove directly from the water. The bacteria may grow out of sight (inside live rock or sand, in refugia, in tubing, etc.). They may also grow in globs in the display tank. They have to grow somewhere. If they become unsightly, try dosing a different organic that may drive a different set of species that may grow in a different location. I’ve had them often seem to grow on GAC (granular activated carbon media) in a canister filter I previously used, allowing relatively easy export by rinsing the GAC once every couple of weeks.

I’ve never heard any plausible argument why dosing multiple organics at once is desirable, but many people do it and there is likely no harm in doing so. The idea that multiple organics drive a diversity of bacterial species is just speculation, and even if true, I don’t see the benefit.

The bacteria themselves can then be skimmed out, or used as a food for filter feeders, or both (most people probably have both to some extent, unless they do not use a skimmer). The bacteria may grow partly in low O2 regions (such as in sand or rock) and partly in highly oxygenated environments. Since metabolism in low O2 regions uses relatively more nitrate than phosphate compared to metabolism in a high O2 environment, the relative amounts of nitrate and phosphate reduction an aquarists observes may vary from system to system.

Nitrate is always reduced to a greater extent than phosphate simply because bacteria need a lot more nitrogen than phosphorus, but metabolism of organics in low O2 regions may skew it even more, and sometimes can leave the aquarium with little nitrate and an excess of phosphate that they bacteria don’t “want”. In such a case, a phosphate binder might usefully export this remaining phosphate. Alternatively, some aquarists have dosed nitrate directly to the aquarium to allow the residual phosphate to be consumed.

These linked articles describe vinegar and vodka dosing in more detail.

One potential drawback that may have played a role in some tank problems is that the bacteria that thrive when organic molecules are dosed may be benign (and appear to be in almost all cases), but might actually be pathogenic in others. That is, the added organics may enhance bacterial infections if those bacteria causing the infection (of fish, corals, etc.) are able to take up the added organics and use them to grow faster. I think this risk is low, but it may be real. If you have unexplained problems that might fit this description, and are organic carbon dosing, try not dosing for an extended period.

A second potential drawback of organic carbon dosing is the potential for proliferation of unsightly cyanobacteria in the display tank. There are many species of cyanobacteria, and some can consume the organics we add in this method. If they become a primary consumer, then something may need to be done, such as switching to a different organic compound to dose, or reducing phosphate with a binder such as GFO (granular ferric oxide).
 

ScottR

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Thanks for this. Always learning in this hobby. No matter how many years you can grow acros, you truly never grasp what you thought you knew.
 
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Hal3134

Hal3134

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I’m dosing vodka. Where is the correct chart for that? Is the 10 ml starter dose for vinegar or vodka? I’m using .1ml per 25 gal per the link that Randy provided.
 

taricha

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When I've added novel carbon sources (that hadn't been added to my system before) to sample containers pulled from my system, it took anywhere from 3 to 6 days for a bloom to occur.
I speculate that's a reasonable time frame for bacteria to "catch up" to a new carbon dose regime. If you dose heavy in a time frame shorter than that, you risk an initial bloom that's not well controlled, and could put oxygen at risk.
But after that time frame, the advice to "go slow" is mostly to prevent a rapid reduction in nutrients that everything needs. so you can probably use nitrate and other tests, and obvious tank observations to guide the rate of dose increase after that first week. [Opinion based mostly on my system, others may differ.]
 

Randy Holmes-Farley

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I’m dosing vodka. Where is the correct chart for that? Is the 10 ml starter dose for vinegar or vodka? I’m using .1ml per 25 gal per the link that Randy provided.
I don't think there is such a thing as a "correct" chart for any organic dosing. It all depends on the tank, the nitrate level, what you want to accomplish, etc.. Some folks like to start slow, some don't. I didn't.

That said, the charts in the articles are reasonable starting points.

Here's the vodka one:

 
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Hal3134

Hal3134

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I don't think there is such a thing as a "correct" chart for any organic dosing. It all depends on the tank, the nitrate level, what you want to accomplish, etc.. Some folks like to start slow, some don't. I didn't.

That said, the charts in the articles are reasonable starting points.

Here's the vodka one:

Yep, that’s the article I used. So if we treat the article as guidance but allow for some variation, how fast can I increase my dose and what dose should I start with given my parameters? I’m worried that at theamounts the article recommends it will take a long time to get up to a dose that starts to show improvements.
 
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