instructions please


New member
Hi Randy,

Due to some of the complex things I have seen you post on reef central :D , I need to further my understanding of sugar dosing!

You posted in another thread:

"10 mL of vodka contains about 4 grams of ethanol, which can use up a bit over 8 grams of O2 as bacteria convert it to CO2.

8 grams (8,000 mg) of O2 in 55 gallons (208 L) translates to 38 mg/L of O2. That is many fold more O2 than is present (about 6 mg/L, typically).

So it is likely that the problem was reduced oxygen"

Scary thread!

How much O2 would 1 level tsp of sugar deplete from bacterial processes in 100gallon volume? What about 2 tsp? I think it would be safe to dose enough sugar to consume 2mg/l O2 total per day, whats the dose for that?

All I know is bacteria use O2 and remove N and P. And the average tank contains 7-8mg/l of O2.

Sugar dosing going fine on second day for now. I think 1 level tsp a day(actual measures) is good. But need your math skills :D

Box :)
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New member
8 grams (8,000 mg) of O2 in 55 gallons (208 L) translates to 38 mg/L of O2. That is many fold more O2 than is present (about 6 mg/L, typically

I dont understand the translation part. Is that to say that the 10ml of vodka used up 38mg/l of O2?!

If thats the case, then 1tsp of sugar would use up 9.5mg/l of O2 in a 100gallons of water? And if the typical O2 is 6mg/l then im over by 3.5mg/l.

I just want to use up 2mg of O2 to be safe. So I figure somthing like 1/4tsp of sugar to use up 2mg/l of O2.

Im stumped, can anyone help?

Randy Holmes-Farley

Reef Chemist
Premium Member
Why do you assume that is wrong? The O2 consumption of adding large amounts of easily metabolized organics is high. Aeration, of course, can also pull it in fairly fast.


New member
Yea im assuming that photosythesis of phyto and macroalgae is contributing to a large % of O2. Eric B. describes that.

I didnt assume its wrong, just dont know the math :D

Fwiw, my calculation was wrong, i did it based on 50gallons, while it was 55gallons.

So 38mg o2 usage would be a correct amount for 10ml(or 2tsp of sugar) of vodka in a 55gal?

I have been pondering also on the amount of O2 increase by decreasing temp from 82 to 80f, and possibly reducing SG from 1.026, but that is drastic. I can just keep my dose lower.


It's what it's
What does the addition of vodka and suger do to a saltwater fishtank? I'm not sure I understand what it is being used for. N and P, what does that stand for above?

Mike O'Brien

New member
Nitrate and phosphate. The vodka add's a free carbon source. If carbon is limiting in the tank it will drive bacterial growth and in doing so the growing bacteria population will consume these nutrient's and hopefully be skimmed out of the tank.

There are a few commercially available method's that use this same principle, and there are sure to be more.

This bring's me to a question.
Are there really zeolites that preferentially bind ammonium in salt water ?

Mike O'Brien

New member
Too bad. That's what I thought though.

I just wonder how companies can market them claiming it will remove ammonia from both fresh and salt water. Like Pura complete. I use GFO to run the effluent from my calcium reactor through. last time I went to pick some up all they had was the pura complete wich is a mix of GFO, zeolite and GAC. I'm hesitant to use it because of the possibility that it will bind up alot of calcium.

What do you think ?