Kalk Q?

[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/sh...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/sh...ht=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

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.

Cheers,

Chris

[Myka]

Uhm...dangit you chemists talking over my head. 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. 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.

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]

Originally Posted by 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.

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


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. 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. 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.