Glycerine as a carbon source

[Ryengoth]

I've been giving some major thought to dosing glycerine instead of the other carbon sources. It's far more concentrated, has a longer consumption period and will not affect PH or cause damage to tissue. It irritates coral, but it will sink to the bottom quickly and dissolve. Any recommendations for testing methologies? I have a 10G QT tank I'm going to be doing some algae testing in soon, so I will be able to dose po4, no3 and no4 and glycerine in clean water.

 

[toaster77]

For, glycerine (glycerol) yes you can find solutions that are more concentrated than the active carbon source in vinegar (acetate, 5%) or vodka (ethanol, 40%)
Glycerol has three carbons as opposed to two carbons in vinegar or vodka. It is metabolized differently than vinegar or vodka. It may have some similar effects, but just know that nearly all species in your tank will likely be able to take up and utilize glycerol. It is a component of lipids and cellular membranes. For vinegar and vodka, many bacteria have a pathway to build more complex molecules from these carbon sources that higher eukaryotic species do not have.

 

[Ryengoth]

So, you could dose a mix depending on the dissolved nitrogen and phos levels and focused use.

 

[toaster77]

It should be quite safe to dose alone or in combination with other carbon sources, but I'm unsure whether you'll see beneficial effects specifically due to the glycerol as everything in your tank will use it. Can't hurt to try...

concentrated glycerol solutions (i.e. 95%+) are also very viscous, you may need to dilute with water a little bit to make it easier to handle or dose.

 

[Ryengoth]

I'm actually using USP 99.7% for peroxide mixing to spot-treat GHA. 2 parts h2o2 and 1 part food grade veg glycerol as a weight and "time delay". I noticed the bacterial bloom timing varied differently than when I used to dose Vodka and also when using 5% white vinegar. It lasted much longer and the response was quite higher in the skimmer.

 

[Randy Holmes-Farley Verified Community Expert]

I'm not sure I see any big advantage to dosing it, but it is certainly a fine experiment.

I don't see how one would pick different carbon sources based on nutrient levels, or, really, why concentration matters.

 

[Ryengoth]

The speed at which it's consumed and the density made a difference in the exporting results. It could be due to substrate penetration from it sinking during my peroxide mix testing. The substrate browned up first and then quickly spread. I don't have anything quantifiable yet, except that dosing more than 50ml of it in 100g over 48 hours hours caused a massive diatom explosion that lasted a week. I'm a pro at cleaning filter socks now.

 

[Randy Holmes-Farley Verified Community Expert]

You think glycerol is taken up faster than acetate? How do you know?

 

[Ryengoth]

Slower, not faster, based on the length of time the bloom occured and the volume of export. Need more testing.

 

[Ryengoth]

I dosed 5ml a day of vodka in my 29g biocubes and got light brown water in the skimmer. Some bacterial growth enhancement but it wasn't massive. Diatom growth on the glass was minimal. That's 17% by volume. I dosed right at 50ml of glycerine for a TWV of 120G once and got a full bucket of black sewage water daily for almost 6 days. That's 41% by volume, but it was not dosed on a daily basis.

 

[biom]

if you are dosing vodka you add already glycerol and sugar: vodka is mixture of carbon sources

ingredients (at least in some east european brands) in 1 ml of 40 vol% vodka:
0.6 ml water
0.4 ml ethanol
1.5-2 mg sugar
1 mg glycerol
0.05 mg baking soda
0.025 mg citric acid

 

[edosan]

BUMP

I do dose Glycerol on a weekly basis, since I start my reef...arrond 10ML USP. works great as carbon source...and not sure but corals might take some to probably (since is also a by product of zoax).

 

[Randy Holmes-Farley Verified Community Expert]

BUMP

I do dose Glycerol on a weekly basis, since I start my reef...arrond 10ML USP. works great as carbon source...and not sure but corals might take some to probably (since is also a by product of zoax).

Why did you elect it over other compounds?

 

[edosan]

Hello Randy:
I have try all compounds (Biopellets, vodka, vinegar, sugar all works) also I have read the coral glycerol uptake from zoaxantellae, and I figure: Why not dose Glycerol? might be good for bacteria and also for corals, been there over a year and no problems what so ever, and my polyps on SPS are very opened. I do not have much cientific data to share tho, and I know it might be something else, but there is no detrimental use for it at least in my reef. Too much Glycerol it will make the skimmer crazy for a few minutes tho.

I had USP Vegetable Glycerol in my inventory so I figure to give it a try (from my old days of e-cigarrete liquid mixing...I quit that)

 

[Randy Holmes-Farley Verified Community Expert]

OK, sounds good. Thanks.

 

[RobBaglieri]

This may be a dumb question....why not just dose glucose or galactose? Plenty of Carbon, readily broken down and would not effect pH.

 

[edosan]

For bacteria any sugar source works... I belive the conversion is sugar - alcohol - vinegar - acetate & acetate is good for bacteria. Not an expert tho. (is just my understanding, I might be wrong)

 

[Randy Holmes-Farley Verified Community Expert]

This may be a dumb question....why not just dose glucose or galactose? Plenty of Carbon, readily broken down and would not effect pH.

All carbon sources potentially lower pH becuase they all end as CO2. It is just with vinegar that you get more of the drop at the beginning, but the overall acid added is the same.

That said, I prefer acetate because it is very easily taken up by many organisms (even large ones), is the most natural in the sense that it is the largest turning over organic in natural sediments, is cheap, and it works well.