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.
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]

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

[Aquattro]

Chris, acetic acid,CH3CO2, does in fact contain CO2. The acetate is used as a carbon source and will increase carbonates in solution.
I'll look up Craig's article on it, it will go into depth that I no longer remember :)

[Aquattro]

Chris, I'll assume your the Chris88 in this thread.. http://www.reefcentral.com/forums/showthread.php?p=15912606

The post above your last comment explains the addition of carbon via acetate, and how it increases solubility of CaOH by 36%.

This is quoted from Craig Bingman in the Reef Aquarium, vol 3. I've also seen detailed articles by him explaining the reaction fully.

[Canadian]

Hi again Brad,

I quickly scanned through some info on the kalk slurry method and it appears the method is most appropriate for tanks without exceptionally high Ca demands. Higher Ca demand tanks would require multiple doses of kalk slurry while carefully monitoring the effect on pH. It also doesn't appear that this would be a particularly effective way of raising Ca, especially in those tanks that are either large or have very high Ca demands. I didn't see where Myka was asking about raising her Ca - I was just under the impression she is looking for a way to dose Ca and Alk without needing Mg and doing so with kalk.

However, depending on what you read there seems to be a bit of contradictory information about whether this method is best for tanks with high Ca demands versus typical demands. Some reports suggest it's good for high Ca demanding tanks where supersaturated dripping is inadequate, while other reports indicate it's best for lower Ca demands due to the effect on pH.

Here's some more info from Anthony Calfo:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=638828&highlight=kalk+slurry

If someone was to attempt to employ this slurry method I think the most prudent course of action would be to first determine daily Ca demands, perform the necessary calculations for how much kalk slurry is needed to maintain that level, and then divide that dose into smaller ones to monitor the effect on pH. If the effect on pH is within reason (less than 0.2) then fewer and larger doses could be trialed.

[Funky_Fish14]

Sorry, but thats not me. I use the same username as this one(Funky_Fish14) on RC.

Btw Brad, you wrote the molecular formula for acetate as opposed to acetic acid in the first of your last two posts :razz:

Acetic(Ethanoic) acid does not 'contain' CO2. There are however multiple ways acetic acid may be written.

A) CH3COOH
B) H3CCOOH
C) C2H4O2
D) CH3CO2H
E) HC2H3O2

The most common/accepted forms are CH3COOH and CH3CO2H. Some prefer to write the latter as H3C2O2H because this matches the molecular structure the best. Ofcourse all the numbers would be written as a subscript. None of these forms 'contain' CO2. There is a very large difference between the molecular formula and the molecular structure. If this was true, many other substances could also be said to 'contain' CO2.

I spoke to some chemistry profs about this topic, here is where the CO2 comes from in the reaction.

Excess Ca(OH)2 reacts with the little amount of CO2 in the water to produce bicarbonate ions. Excess reactions occur (because there is no CO2) and produce Bicarbonate ions. Bicarbonate react with calcium and create Calcium Carbonate and water. The Acetic acid has a tendency to react only with the Carbonate ions that are formed, as opposed to with the hydroxide (OH) ions, which in turn produces a bunch of CO2 required for the reaction with the Calcium Hydroxide (Kalk). This explains why the acetic acid works to dissolve the kalk. That is why it allows a large dose all at once to work. However, dripping a kalk solution in to the water slowly will work fine as well, because the Calcium Hydroxide has enough CO2 throughout the aquarium water to react with and dissolve correctly.

In my previous post in this thread, I had yet to see anywhere online offer any explanation as to why the acid would not react with the base (calcium hydroxide, kalk) right off the bat. My chem profs were able to explain why it works and why it has a tendency to avoid reacting with the Ca(OH)2 immediately. This post clarrifies my last point in my last post, and why adding acetic acid works. So what I initially explained about acid not working was wrong(I knew that it did work in practice, but chemically didnt make sense?), but, apparently it takes a heck of a lot more chem knowledge to understand why its happening. :razz:

Cheers,

Chris

[Myka]

Uhm...dangit you chemists talking over my head. :twised: I'm kidding.

To clarify, I ran out of plain calcium and only have calcium with magnesium in it. My magnesium is at 1475 ppm, so obviously I don't need to add any more magnesium. :lol: So I was hoping I could just add a Kalk slurry, but from these posts it looks like I would cause too great a pH spike as I need to provide about 20 ppm calcium and 1 dKH per day.

[Funky_Fish14]

What is your pH at?

[Myka]

I don't test pH. I am picking up a pH pen tomorrow though. I will test it and let you know. I haven't tested pH in years.

[Delphinus]

You could always consider a couple degrees in chemistry. :p

Actually I remember my chem classes in university as being the most fun. Mostly because we were blowing things up. One of the chem profs was clearly insane. I fondly remember his demonstration of hydrogen and oxygen bonding to form water. It was a huge lecture hall and even in the back of the class I felt the shockwave blow my hair back (yes I had hair once - it was the early 90's and I had it in an artsy ponytail and I wore black turtlenecks and bracelets - the chicks totally dug that.) Too bad that organic chem was one of the hardest things I've ever worked on and I barely survived that course with a C- forever dashing any hopes and dreams I had of going on to med school. But it does come in handy when trying to understand posts like Brads and Chris's.

[Funky_Fish14]

I don't test pH. I am picking up a pH pen tomorrow though. I will test it and let you know. I haven't tested pH in years.

Oh wow, haha. Alright.
(Im no better though, I last tested my pH a few months ago :lol: - my @ home test kits are expired even :lol: )


Myka, I think if you drip a small amount in the tank over a period of time, it should actually be fine. I dont think you will affect your pH very much. However I guess your pH should be identified before you give it a shot, haha. :wink: As then you can also track it. You could mix a weak solution and let that drip when you do try it at first. With a slow drip (into an area of high waterflow), the reaction will proceed correctly without the need for dabbling with anything other than pure water (use RO water if you can) and the kalk.

Hope that helps :)

Chris

[Funky_Fish14]

LOL Tony! Doesnt it make it fun?

I dont know if being in organic chem courses makes it any easier to understand. :silly: There are 'rules' that are always the same, and you are let to believe its simple to understand, then just as you think it applies to an entire chemical group, you discover the other 34 rules that apply to each other part. Hah. Even the profs often get stumped. :razz:

[Myka]

I got some plain ole calcium today, so no need to mess with the Kalk now. :D

Oh wow, haha. Alright.
(Im no better though, I last tested my pH a few months ago :lol: - my @ home test kits are expired even :lol: )

I don't test pH because it's not overly important, like testing nitrite. If everything else is on target, and I'm using a skimmer it's impossible for pH to be so out of whack that it will affect anything.

I got the pH pen today, but it's calibrated with pH 4 and 7 fluid for freshwater, so I need to get some pH 7 and 10 calibration fluid for saltwater.

[SeaHorse_Fanatic]

For what its worth, I use a 2L juice jug, add several tablespoons of kalk, add water, let sit for 1 hour at least, pour the semi-clear solution into the sump but not the concentrated slurry on the bottom.

I do this several times a day into my 210g with 75g sump with no problems & good coral growth in a heavily stocked (both corals & fish) display with a high calcium requirement.

On some of the sps, am achieving at least a cm/month growth.

Anthony