More on Calcium acetate

[MRosendo]

Randy:

After a lot of reading (thanks for it all), I´ve decided to use calcium acetate to keep my alk and calcium levels. I´ve also determined the daily need for my tank (around 6 g. of calcium acetate dihidratated), and now I would like to automate it. I´ve considered disolving it in water and using a dosing pump to do the task. My question is about the acetate solution: is there any limit I must consider (solubility, degradation of the solution, etc)?. My idea is that, although I check levels weekly, from time to time I will leave the system unattended up to four weeks, so it should last at least 23- 25 days.

Thanks for your help.

[Randy Holmes-Farley]

It is very soluble, but the solution may be degraded as bacteria consume the acetate. I don't know how fast that happens.

Slow dosing and dosing during the daylight hours is a good idea, IMO, to reduce any rapid drop in O2 as bacteria in the tank consume it.

[MRosendo]

Thanks for your quick answer.

I will try to evaluate the degradation of the solution. To do so, is there a way to measure its power?. I understand that, if the acetate is consumed, the solution will be oversaturated with Calcium, so it will occasionally precipitate. Is that OK? Can this be a good indicator?

Appart from keeping it air tight and in a dark place (no possibility of keeping it cool), is there any other thing I can do to try to avoid the degradation?

Best regards.

[Habib]

My idea is that, although I check levels weekly, from time to time I will leave the system unattended up to four weeks, so it should last at least 23- 25 days.


I think that this might be problematic; bacteria and mold growth.

[Randy Holmes-Farley]

Look for bacterial growth. Monitor pH. Look for CaCO3 precipitation (that's the biggie, IMO).

Bacteria will convert the acetate into HCO3-, that is how CaCO3 might precipitate.

I'm not sure how to slow bacterial growth in a way that is acceptable to dose to the tank. High concentration of calcium acetate will do it, but if you dilute it for dripping, the risk becomes higher.

[Jens Kallmeyer]

HI MRosendo, Randy

I wouldn't worry about bacterial acetate degradation too much. It will eventually happen, yes, but for this purpose and within a time period of a month or so it should not matter too much. We have acetate solutions in our lab that sit in the fridge for longer than a month (not the calibration standards, though, they are made fresh each time). You could try to sterilize the glass and boil the water that you use to make up the solution. This should definitely be sufficient to keep things in the right condition. As you already said, store the stuff in a closed container and in the dark.

Cheers

Jens

[MRosendo]

Thanks, Jens.

This weekend I will try to put everything in place, and experience will tell us a lot.

Regards,

Miguel (MRosendo)

[Mislav]

What is calcium acetate and what for is it used when not used in reef aquarium?

[MRosendo]

What it is, I ´m afraid is difficult for me to explain (chemistry & english!!). How it is, its a white powder similar to the one used for the dish washer or the washing machine (that is, more like sugar than like flour). I buy it in a chemical products shop, with a USF quality.

What it is used for, it has different uses in medicine and its also used in the food industry, as a preservation additive (it can be identified, at least in Spain, as E-263), mainly in bakery.

[Jens Kallmeyer]

Originally posted by MRosendo
Thanks, Jens.

This weekend I will try to put everything in place, and experience will tell us a lot.

Hi

Please keep us informed

Cheers

Jens

[Randy Holmes-Farley]

What is calcium acetate and what for is it used when not used in reef aquarium?

It is the main calcium and alkalinity supplementing agent in one commercial product, Salifert's All-in-One.

I discuss it in this article:

How to Select a Calcium and Alkalinity Supplementation Scheme
http://www.advancedaquarist.com/issues/feb2003/chem.htm

from it:

"One-part balanced additive systems: Calcium Acetate

Calcium acetate is a product that has gotten relatively little publicity despite its apparent ease of use and the commercial availability to aquarists. In some ways it is similar to the combination of limewater and vinegar.16 When dissolved in water (fresh or salt), you have calcium ions and acetate ions. The acetate is rapidly metabolized by tank organisms to form bicarbonate, carbon dioxide, and water:

CH3COO- (acetate) + 2 O2 ---> HCO3- + CO2 + H2O

This equation suggests that pH of such tanks may stay near the low end of normal, because of the excess carbon dioxide, but the practical experience of people using calcium acetate suggests that this is not a big concern.

Calcium acetate may also facilitate the conversion of nitrate to nitrogen gas (N2)16 in anoxic regions of live sand and rock by providing the carbon source necessary for the process (but this has not been demonstrated one way or the other). The equation below shows the process that could take place:

5 CH3COO- (acetate) + 8 NO3- ---> 10 CO2 + 4 N2 + 13 OH- + H2O

One of the sources of calcium acetate to aquarists is Salifert’s All in One (a product that also contains some strontium, amino acids, and some trace elements). It is a liquid product that can be poured directly into a tank with no immediate concerns about pH. The current version of their commercial product is 250,000-mg/L calcium acetate, so it contains the equivalent of 3,160 meq/L of alkalinity. This products sells in the US for about $31.50/L. Consequently, it costs about $10.00 per thousand meq/L of alkalinity. That price makes it very expensive for a tank with a large demand for calcium and alkalinity, but the zero initial costs make it attractive for small tanks, especially nano-reef tanks.

I have no information on the purity of the material, or the exact nature of the “trace elements� in it. Everything in the bottle will be delivered to the tank. It poses no unusual safety concerns. The upper limit to how much calcium and alkalinity can be supplied to a tank in this fashion depends on two factors. If the metabolism of acetate is rapid and the dose is very high, oxygen might be depleted. If the conversion is slow then acetate can build up in the tank (not itself a significant concern except perhaps at very high levels where it might confound an alkalinity test2). Habib Sekha of Salifert has indicated that using the doses recommended on the bottle will not lead to either of these issues being problematic.

Overdosing is not expected to be an unusual problem, but if one makes significant additions in this fashion, the alkalinity will take time to show up completely in the tank because the acetate takes time to be metabolized. Consequently, I’d wait a day after adding it to measure alkalinity. Calcium measurement won’t be similarly impacted. Tank salinity will not increase over time using calcium acetate."

[Randy Holmes-Farley]

Just to follow up, calcium acetate has lots of uses, but is not inexpensive. The Merck Index lists uses as : manufacture of acetic acid, acetone, in dyeing, tanning, and curing skins, in lubricants, as a food stabilizer, and as a corrosion inhibitor.

[baruchbl]

Calcium acetate can be very dangerous. You are playing with fire.
This can cause to bacteria infection. Your aquarium will stinke, the water will be cloudy and your corals will die?

[Randy Holmes-Farley]

Huh?

Lots of folks use vinegar in limewater. Same thing. No stink.

I do agree that bacteria can use the acetate, and may mutiply and use up some O2 (as I mentioned above). If that happens, by all means stop or reduce dosing.

[New Reefer]

I've used calcium acetate (analytical reagent grade...) for some time now, and I like it. I'm not sure if it's the added bacteria feeding the food chain, but my tank seems healthyer if I use it.

I add one 5ml teaspoonful of the dry powder on my 300 liter tank, and 2 teaspoons on my 1200 liter system (added into the overflow) every 2-3 days.

I did notice an increase in diatom algae growth after I started using it, by my snails and cucumbers easily took care of that...

Hennie