Kalk Q?

[Myka]

Anyone know if I can use Kalk can be used like calcium or alkalinity buffers just by stirring up in some RO and dumping it in? I know you're supposed to wait for it to clear...but why?

I have a container of RowaKalk, but I've never used Kalk, and I need to dose some calcium (and alkalinity) without magnesium. My current calcium product has magnesium in it as well. I'm out of straight calcium.

[Delphinus]

NOOOO! Kalk has a pH of 11, it must be added very slowly, ie dripwise.

Originally Posted by Myka

Anyone know if I can use Kalk can be used like calcium or alkalinity buffers just by stirring up in some RO and dumping it in? I know you're supposed to wait for it to clear...but why?

I have a container of RowaKalk, but I've never used Kalk, and I need to dose some calcium (and alkalinity) without magnesium. My current calcium product has magnesium in it as well. I'm out of straight calcium.

[Myka]

I didn't think such a small amount would alter the tank's pH...doesn't calcium have a really high pH too?

[Aquattro]

The high pH is a result of the OH ions, which are not part of a typical Ca additive. Now you could add a very small amount without affecting pH (dependant on alk levels), but I'm not sure you could add enough to significantly affect Ca levels. I've never used CaOH to raise levels, only maintain them on a drip top off system. I'd probably not try it without doing a whole bunch of math first.
I did the math once before to figure out how much muriatic acid I could add to the tank without affecting pH (aptaisia control) and it was a very small amount in a 90g system.

[Canadian]

You can dump it straight in to a sump if you ensure you're not dosing large amounts that will drive pH up by more than 0.2. Dosing a kalk slurry was popularized by Anthony Calfo and it has some reported benefits. I've never employed this method but there are a lot of hobbyists who have without killing their livestock.

From wetwebmedia.com:

Kalk dosing
Hello and thanks for all of your helpful hints and suggestions!! I am now bringing my pH up to acceptable levels with the Kalk dosing. Was 7.9 and now am keeping it up to 8.25 regularly.
<good to hear... do check recent posts on the FAQs also about low pH and well insulated houses (atmospheric influence) and opening a window to raise pH in the aquarium!>
The question I have with the Kalk "slurry" is: Do you mix up the solution and then dump all contents from the glass into the aquarium or do you pour it slowly and stop when the undissolved Kalk starts dripping in? This has been a bit vague in your Q&A forum.
<no worries... both ways can be done. I elaborate on this application in my Book of Coral Propagation if you are inclined. The gist of it though is that it is not so much a matter of slurry or decanted solution, but rather what is your daily demand for calcium (go three days without any dosing and measure calcium before and after then divide by three to get a daily average). Once we figure out how much calcium is needed daily, we then need to slowly dose calcium to fulfill that demand (confirmed by testing that reveals the calcium level isn't straying downward with your x mg of Kalk daily). You could begin with an eight or a quarter of a teaspoon daily (probably a little low if you have a good bit of live rock and/or coral). The only limiting factor here is that regardless of what your daily demand for calcium is, you should never add more slurry or decant than your pH can sustain without jumping my more than .1-.2 (i.e.- before slurry 8.2, after slurry 8.35). For such measures and experiments with Kalk slurries, accurate pH testing equipment is necessary (digital pen or meter). It is uncommon that your tank will not be able to get all of its daily calcium needed through a single dose without spiking pH. Only tanks with massive coral loads need a second dose or more. Remember to only dose Kalk after the lights are out tooThanks as always, Jeff Reed>
<best regards, Anthony>

And here's a link to lots of answers to kalk questions by Anthony Calfo. Many of them pertain to dumping in a slurry:

http://www.wetwebmedia.com/kalkh2ofaqs.htm

[Aquattro]

Andrew, without reading the links, this article appears to imply supplying the daily required Ca, not increasing levels. Can enough be added to increase levels beyond daily consumption? I can't read it all now, apparently my employer requests my presence

[Chin_Lee]

Brad - are you aware of any calculations on how much more kalk can be dissolved to raise the saturation level by decreasing the pH (by adding vinegar/muriatic acid)?

I have been adding muriatic acid into my kalk reactor in hoping to maximize the saturation levels of ca/alk on the output. I usually put about 1" of kalk powder at the bottom of the reactor. At one time, I added some acid and it definitely dissolved more kalk (I know this because all the whitish buildup on the walls dissolved and cleared up). The pH in the reactor was down to 3.5 but at a certain point, no more kalk was being dissolved and the ph stayed at 3.5. Obviously in this instance I had added too much acid. Essentially what I would like to know is how much more beneficial am I in doing this? Does the saturation level increase dramatically?

[Aquattro]

Chin, I used to add vinegar to my slurry, and I can't say that it gave me any noticeable advantage. I suspect that the acetic acid may have had secondary effects, such as a food source for bacteria, but my kalk experiences were pretty much the same with or with out. I used 5g jugs though, not a reactor. Also, I added enough kalk to the jug to have excess, even with the vinegar, so I'm not sure how much more actually dissolved. I believe Craing Bingman has the calculations somewhere, but it was years ago that I read about it.

[Canadian]

Originally Posted by Aquattro

Andrew, without reading the links, this article appears to imply supplying the daily required Ca, not increasing levels. Can enough be added to increase levels beyond daily consumption? I can't read it all now, apparently my employer requests my presence

Hey Brad,

I wrote that message this morning while I was getting ready for work and now I'm at work (writing a report between patients). I'll take the time to reply thoroughly when I get home from work.

[Funky_Fish14]

Hey Guys,

Chemially (in terms of writing out the reaction), adding the acid to Kalkwasser is actually removing the alk/carbonate buffering capacity of the water. Adding acid to a base creates (water) and a (salt). Because you are not getting any CO2 in that part of the chemical reaction, no carbonate is formed. If the point of adding Kalkwasser is to increase carbonate/alkalinity, then I think the purpose is defeated by adding the acid. You will however end up with calcium ions in the water as the 'salt' formed will seperate/dissolve (this litterally means the compound dissolves into its separate elements as it is in water, not simply sitting as a 'bunch').

Allowing the Kalkwasser to simply dissolve in water (with CO2 present) will create calcium ions and carbonate ions. This will achieve both purposes at the same time.

Although there are some exceptions, like while in aquarium water, there are always other compounds present, the primary reaction with the acid will not produce carbonate ions.

Im not sure how this pans out in a 'real' setting in the aquarium, but 'mathmatically' (or chemically speaking), I dont think the acid helps to create an alkalinity buffer.

Cheers,

Chris




- I am going to ask my chem lab teacher about this in about half an hour and see what I can get. I've seen an explanation suggesting adding acid 'creates' CO2 in the water, which does not make sense. Adding an acid to water does not make CO2... - Will update.

Chris