question for all you chemists out there (calcium hydroxide)

[hawaiiguy]

Ok, I've read threads that describe the use of calcium hydroxide (usually neutralized with acetic acid). I'm a big fan of DIY so rather than by a calcium reactor, I like the idea of a homemade source of Ca(OH)2. I went to my local hardware store to check out their lime mix and here's the ingredient list:

Neutralizing value as CaCO3 eq, min (%): 131.51
Calcium (Ca), min (%): 51.88
Calcium Carbonate (CaCO3), max (%): 4.0
Calcium Hydroxide (CaO) min (%):95.9
Magnesium (Mg), min (%): 0.37
Magnesium Carbonate (MgCO3), min (%): 0.0
Magnesium Oxide (MgO), min (%): 0.62

Any problems here? Technically, what they call calcium hydroxide is actually calcium oxide but I think when it mixes with water it should get hydrated to Ca(OH)2.

CaO + H2O ---> Ca(OH)2

is that correct?

My concern is the reactivity of Magnesium hydroxide... I'm unsure of the chemistry here but I believe the MgO will hydrate to Mg(OH)2 just like the CaO above. Then, if I'm neutralizing it with vinegar the reaction should proceed like this:

Mg(OH)2 + 2 CH3COOH ---> Mg+2 (aq) + 2 CH3COO- (aq) + 2 H2O

This would be similar to the reactivityof calcium hydroxide right? Creating free magnisium ions would be a good thing right?

Anyways, If anyone has any insights about this ingredient list or the chemistry involved, I'd love to hear them

[dirtyreefer]

Dude, you lost me at Ca(OH)2

Just kidding, however I have seen people use vinegar (the acetic acid you mentioned) being used to neutralize Kalk. You can buy Kalk as "pickling lime" which is I believe is only sold in the states in that form, however alot of people buy bulk Kalk all the time.

I think you can also use epsom salts for a source of Mg. You should check the Reef Chemistry forum on RC, Randy has some good homemade recipes to supplment Ca, Alk, pH, and Mg.

[Beverly]

Wow! Someone who actually knows chemistry At least far, far, FAR better than I
While I'm not a big DIY-er, his link should point you in the right direction for DIY additives...

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System:

http://reefkeeping.com/issues/2006-02/rhf/index.php

[hawaiiguy]

thanks for the links... I think I'm going to go ahead and try the lime mix I have, I just need to figure out the stoichiometry here. Wish me luck I'll let everyone know how it goes.

[BMW Rider]

Originally Posted by hawaiiguy

Ok, I've read threads that describe the use of calcium hydroxide (usually neutralized with acetic acid). I'm a big fan of DIY so rather than by a calcium reactor, I like the idea of a homemade source of Ca(OH)2. I went to my local hardware store to check out their lime mix and here's the ingredient list:

Neutralizing value as CaCO3 eq, min (%): 131.51
Calcium (Ca), min (%): 51.88
Calcium Carbonate (CaCO3), max (%): 4.0
Calcium Hydroxide (CaO) min (%):95.9
Magnesium (Mg), min (%): 0.37
Magnesium Carbonate (MgCO3), min (%): 0.0
Magnesium Oxide (MgO), min (%): 0.62

Any problems here? Technically, what they call calcium hydroxide is actually calcium oxide but I think when it mixes with water it should get hydrated to Ca(OH)2.

CaO + H2O ---> Ca(OH)2

is that correct?

My concern is the reactivity of Magnesium hydroxide... I'm unsure of the chemistry here but I believe the MgO will hydrate to Mg(OH)2 just like the CaO above. Then, if I'm neutralizing it with vinegar the reaction should proceed like this:

Mg(OH)2 + 2 CH3COOH ---> Mg+2 (aq) + 2 CH3COO- (aq) + 2 H2O

This would be similar to the reactivityof calcium hydroxide right? Creating free magnisium ions would be a good thing right?

Anyways, If anyone has any insights about this ingredient list or the chemistry involved, I'd love to hear them

Ummmm..... I'm sorry, I wasn't listening, can you repeat the question.... In english this time.

I can see that my retention of high school chemistry is about nil.

[Beverly]

Originally Posted by BMW Rider

I can see that my retention of high school chemistry is about nil.

At least you have high school chemistry I flunked out of Chem 10

[BMW Rider]

Originally Posted by Beverly

At least you have high school chemistry I flunked out of Chem 10

I did ok in Chem 30, but that was more than half a lifetime ago. Still, it was nowhere near this level.

I think a good place to ask this question is in the Chemistry forum at Reef Central.

http://reefcentral.com/forums/forumd...s=&forumid=112

You'll probably get a response that is at least helpfull there

[Ruth]

Originally Posted by hawaiiguy

Neutralizing value as CaCO3 eq, min (%): 131.51
Calcium (Ca), min (%): 51.88
Calcium Carbonate (CaCO3), max (%): 4.0
Calcium Hydroxide (CaO) min (%):95.9
Magnesium (Mg), min (%): 0.37
Magnesium Carbonate (MgCO3), min (%): 0.0
Magnesium Oxide (MgO), min (%): 0.62

Any problems here? Technically, what they call calcium hydroxide is actually calcium oxide but I think when it mixes with water it should get hydrated to Ca(OH)2.

CaO + H2O ---> Ca(OH)2

is that correct?

My concern is the reactivity of Magnesium hydroxide... I'm unsure of the chemistry here but I believe the MgO will hydrate to Mg(OH)2 just like the CaO above. Then, if I'm neutralizing it with vinegar the reaction should proceed like this:

Mg(OH)2 + 2 CH3COOH ---> Mg+2 (aq) + 2 CH3COO- (aq) + 2 H2O

This would be similar to the reactivityof calcium hydroxide right? Creating free magnisium ions would be a good thing right?

Anyways, If anyone has any insights about this ingredient list or the chemistry involved, I'd love to hear them

I think the only thing I can say is HUH?

[hawaiiguy]

I guess my excuse is that I'm finishing my biology undergrad right now and I've gone pretty heavy on the chemistry for the past 4 years (I could probably minor in it; haven't really checked) It's still fresh in my mind (shudder...)

I have been doing some reading at reefcentral and reefs.org and I've decided the mix I have is safe... I just dosed my tank with about 10mL of the stuff so we'll see what happens (so far, so good)...

[Buccaneer]

So what hardware store and what is the brand of lime-mix you are using ?