Is vodka more effective than vinegar for nitrate reduction?

[Miami Reef]

First, a little anecdote.

I dosed 15mL of a DIY NOPOX (75% vinega; 25% vodka) in my 260 gallon tank. It dropped my nitrates to undetectable and I even had to dose about 10ppm a few times to get nitrates from going too low.

Fast forward to today, I am currently only using vinegar and I just started dosing around 100mL per day. I went from 60mL and I really am seeing no reduction in nitrates, if anything, it’s slowly climbing

I did the math, on a carbon bases, the amount if carbonI’m dosing is higher with vinegar only than the vodka/vinegar mix.

It almost seems like the denitrifying bacteria in my tank preferred the vodka?

Or maybe the cryptic sponges that I have are outcompeting the bacteria for carbon?

Or maybe I just need to be more patient for the denitrifying bacteria to populate (are there different types of denitrifying bacteria that prefer different carbon sources?)

 

[Oregon Grown Reef]

First, a little anecdote.

I dosed 15mL of a DIY NOPOX (75% vinega; 25% vodka) in my 260 gallon tank. It dropped my nitrates to undetectable and I even had to dose about 10ppm a few times to get nitrates from going too low.

Fast forward to today, I am currently only using vinegar and I just started dosing around 100mL per day. I went from 60mL and I really am seeing no reduction in nitrates, if anything, it’s slowly climbing

I did the math, on a carbon bases, the amount if carbonI’m dosing is higher with vinegar only than the vodka/vinegar mix.

It almost seems like the denitrifying bacteria in my tank preferred the vodka?

Or maybe the cryptic sponges that I have are outcompeting the bacteria for carbon?

Or maybe I just need to be more patient for the denitrifying bacteria to populate (are there different types of denitrifying bacteria that prefer different carbon sources?)

Be patient. It took 3-4 weeks of dosing vinegar before I found the right dosage, but it definitely works. It's been 3 weeks since I found that dosage amount and my nitrates have dropped 13ppm from 27ppm to 14 ppm.

 

[Miami Reef]

Be patient. It took 3-4 weeks of dosing vinegar before I found the right dosage, but it definitely works. It's been 3 weeks since I found that dosage amount and my nitrates have dropped 13ppm from 27ppm to 14 ppm.

Thank you,

What was the dose? Was it the 1mL/gallon dose?

 

[Oregon Grown Reef]

Thank you,

What was the dose? Was it the 1mL/gallon dose?

For me it's 0.7 ml per gallon for a total of 35ml for 50 gallons of system volume.

 

[Miami Reef]

For me it's 0.7 ml per gallon for a total of 35ml for 50 gallons of system volume.

Oof,

If I dosed 0.7mL/gallon I’d have to dose 182mL a day.

I’ve been only dosing 60mL for about 2 weeks (I took my time with ramping).

 

[Oregon Grown Reef]

Oof,

If I dosed 0.7mL/gallon I’d have to dose 182mL a day.

I’ve been only dosing 60mL for about 2 weeks (I took my time with ramping).

I was going way too slow at first. You could probably increase the dosage by 5ml every 3 days.

 

[Randy Holmes-Farley Verified Community Expert]

I have not seen any evidence that there’s a clear difference in nitrate reducing capability of ethanol vs acetate in general, but ethanol does have more energy per molecule available from metabolism than does acetate.

 

[Miami Reef]

but ethanol does have more energy per molecule available from metabolism than does acetate.

What do you mean by this? Are is this quote referring that vodka is 8x more potent than vinegar?

Edit: phone typo.

 

[Randy Holmes-Farley Verified Community Expert]

What do you mean by this? Are this quote referring that vodka is 8x more potent than vinegar?

No, that is just a concentration comparison in vodka (40% by weight) and vinegar (5% by weight).

It means that a single molecule of ethanol contains more energy than acetic acid. That doesn't mean it is necessarily better at reducing nitrate, even on a per molecule basis, but it means that organisms might be driven to grow more from using a single molecule of ethanol compared to a single molecule of acetic acid, and that might use more nitrate.

We discuss it here:

Reef Chemistry Question of the Day

This is the first of hopefully many Reef Chemistry Questions of the Day. Some will be easy, and some will be harder. We'll start very hard, just for fun, :D First question: Some reefers dose vinegar, and some dose vodka to drive bacterial growth and reduce nutrients. Considering just the...

www.reef2reef.com

This is the first of hopefully many Reef Chemistry Questions of the Day.

Some will be easy, and some will be harder.

We'll start very hard, just for fun,

First question:

Some reefers dose vinegar, and some dose vodka to drive bacterial growth and reduce nutrients.

Considering just the primary organic molecule present in each, and ignoring the concentration/amount of water in each, which of these two organic molecules packs more energy per unit of weight when fully metabolized with oxygen to CO2 and water?

Good luck!

 

[Miami Reef]

No, that is just a concentration comparison in vodka (40% by weight) and vinegar (5% by weight).

It means that a single molecule of ethanol contains more energy than acetic acid. That doesn't mean it is necessarily better at reducing nitrate, even on a per molecule basis, but it means that organisms might be driven to grow more from using a single molecule of ethanol compared to a single molecule of acetic acid, and that might use more nitrate.

We discuss it here:

Reef Chemistry Question of the Day

This is the first of hopefully many Reef Chemistry Questions of the Day. Some will be easy, and some will be harder. We'll start very hard, just for fun, :D First question: Some reefers dose vinegar, and some dose vodka to drive bacterial growth and reduce nutrients. Considering just the...

www.reef2reef.com

This is the first of hopefully many Reef Chemistry Questions of the Day.

Some will be easy, and some will be harder.

We'll start very hard, just for fun,

First question:

Some reefers dose vinegar, and some dose vodka to drive bacterial growth and reduce nutrients.

Considering just the primary organic molecule present in each, and ignoring the concentration/amount of water in each, which of these two organic molecules packs more energy per unit of weight when fully metabolized with oxygen to CO2 and water?

Good luck!

That was an excellent read. Thank you very much. I learned so much.

The only bad thing IME about dosing so much vinegar is that it really takes a toll on the pH. I liked how my vodka/vinegar mix had no noticeable impact on pH, and lowered nitrates.

Spreading out vinegar still caused my pH to be lower than optimal I think. I haven’t even reached the proper vinegar dose to lower my nitrates.

 

[Randy Holmes-Farley Verified Community Expert]

That was an excellent read. Thank you very much. I learned so much.

The only bad thing IME about dosing so much vinegar is that it really takes a toll on the pH. I liked how my vodka/vinegar mix had no noticeable impact on pH, and lowered nitrates.

Spreading out vinegar still caused my pH to be lower than optimal I think. I haven’t even reached the proper vinegar dose to lower my nitrates.

At the end of the day, vinegar dosing and vodka dosing have about the same pH lowering effect, since both end up as pure CO2, with 2 molecules of CO2 per molecule of ethanol or acetic acid. But the vinegar pH effect is front loaded while the vodka pH effect is spread out.

When I was manual dosing vinegar, I could that the pH lowering can be eliminated by saturating it with calcium hydroxide, but that will obviously add a little alk and calcium too.

 

[Miami Reef]

At the end of the day, vinegar dosing and vodka dosing have about the same pH lowering effect, since both end up as pure CO2, with 2 molecules of CO2 per molecule of ethanol or acetic acid. But the vinegar pH effect is front loaded while the vodka pH effect is spread out.

When I was manual dosing vinegar, I could that the pH lowering can be eliminated by saturating it with calcium hydroxide, but that will obviously add a little alk and calcium too.

If I add 200mL of saturated calcium hydroxide in vinegar (5% acidity) in a 260 gallon tank, how much alkalinity am I going to be adding?

 

[Miami Reef]

since both end up as pure CO2, with 2 molecules of CO2 per molecule of ethanol or acetic acid.

Just to make sure I’m understanding this,

I thought I learned that ethanol lowers nitrates with less molecules added compared to vinegar.

So am I correct in the assumption that I’ll need less molecules of vodka compared the same amount of molecules of vinegar to have the same nitrate reducing effect, which means less CO2 being added.

The point I’m trying to understand is this:

While equal molecules of vodka and vinegar produce equal amounts of CO2, dosing ethanol will require less molecules being added than vinegar to have the same nitrate declining effect, which means that vodka will be less likely to lower pH, compared to using vinegar to lower nitrates.

 

[Miami Reef]

I need more molecules of vinegar than vodka to get the same nitrate lowering effect.

That’s what I was trying to say in my blabber above.

 

[Randy Holmes-Farley Verified Community Expert]

I need more molecules of vinegar than vodka to get the same nitrate lowering effect.

That’s what I was trying to say in my blabber above.

I don’t doubt that is a possibility, but it may not be a general result and may relate to the specific organisms in your tank and the actual setup (effectiveness of denitrification in your tank, for example).

 

[Dan_P]

First, a little anecdote.

I dosed 15mL of a DIY NOPOX (75% vinega; 25% vodka) in my 260 gallon tank. It dropped my nitrates to undetectable and I even had to dose about 10ppm a few times to get nitrates from going too low.

Fast forward to today, I am currently only using vinegar and I just started dosing around 100mL per day. I went from 60mL and I really am seeing no reduction in nitrates, if anything, it’s slowly climbing

I did the math, on a carbon bases, the amount if carbonI’m dosing is higher with vinegar only than the vodka/vinegar mix.

It almost seems like the denitrifying bacteria in my tank preferred the vodka?

Or maybe the cryptic sponges that I have are outcompeting the bacteria for carbon?

Or maybe I just need to be more patient for the denitrifying bacteria to populate (are there different types of denitrifying bacteria that prefer different carbon sources?)

How does 15 mL of NOPOX compare to 100 mL vinegar?

15 mL of NOPOX is about 11 mL vinegar and 4 mL vodka. Vodka is about 8X more concentrated, equivalent to about 32 mL vinegar, which means 15 mL NOPOX to approximately equivalent to 43 mL of vinegar. So, I agree you are adding more organic carbon this time.

In my older system, I needed about 1 mL vinegar per gallon for rapid nitrate reduction. This would be about 260 mL of vinegar in your case. From my experience, I would say you were under dosing. Additionally, I would say your observed rapid nitrate reduction at 1/6 the maximum dose is very interesting

 

[taricha]

Spiceymikey found that in practice, it went the other way. On an equal carbon basis, acetic acid reduced nitrates more than ethanol, and he needed 50% more ethanol-carbon than acetic acid-carbon.

Pure Ethyl Alcohol
--------------------------
Instead of trying cheap vodka (which is 60% water) I immediately chose to do what I did with the Acetic acid and went right to pure Ethyl alcohol for the same reason I moved from White Vinegar to Glacial Acetic Acid. I purchased pure Ethyl Alcohol Non-Denatured from LabAlley.com. Based on the well discussed conversion formula of 8-to-1 for 5% White Vinegar vs 80proof Vodka, along with a little math, it seems the carbon density of 100% Ethyl Alcohol and 100% Acetic acid was the same, i.e. 1-to-1). So, I started by dosing the same 10ml of Ethyl alcohol. I found my nutrients were beginning to rise again. For whatever reason, didn't seem to be a true 1-to-1 for me and I ultimately found that I needed about 15ml of Ethyl Alcohol to accomplish the same as 10ml of Glacial Acetic Acid.

which goes to Randy's point that it may not be a generally true result that ethanol lowers NO3 more than acetic acid even if it is true that the energy provided per carbon is greater.
depends on specifics like who eats it and under what conditions etc.

My guess is that if @Miami Reef and spiceymikey had both dosed a carbon source in the same way for a long time, the results might've converged, as populations adapted.