Question about Kalk

[Wildman]

I posted this locally and am looking for a little more info.
http://www.reefcentral.com/forums/showthread.php?t=1900148

[HighlandReefer]

What Your Grandmother Never Told You About Lime
http://reefkeeping.com/issues/2005-01/rhf/index.php#17


From it:

Vinegar And Limewater To Boost Limewater Potency

Another potentially useful attribute of vinegar is that it can be used to help dissolve additional solid lime into limewater. It does this by reducing the hydroxide concentration in the limewater:

10. CH3OOH � CH3COO- + H+

The H+ combines with OH- in the limewater:

11. H+ + OH- � H2O

The actual dissolution of Ca(OH)2 is limited by the multiplication product of the calcium and hydroxide concentrations in the limewater as shown below:

12. Ca(OH)2 � Ca++ + 2OH-

13. [Ca++] x [OH-] x [OH-] � 5.5 x 10-6

where [Ca++] is the concentration of calcium (in moles/L) and [OH-] is the concentration of hydroxide (in moles/L). Consequently, if you reduce the concentration of OH- via equations (10) and (11), then more Ca(OH)2 can dissolve into solution and still meet the equation (13) requirement.

This would seem like a concern, however, since losing OH- might reduce the amount of alkalinity delivered by the limewater. Luckily, this is not the case. While the OH- is temporarily reduced by the acetic acid in the vinegar, when bacteria metabolize the acetate, they release it back to the water:

14. CH3COO- + 2O2 � 2CO2 + H2O + OH-

Consequently, additional solid lime can be dissolved into limewater using vinegar.

How much can be used? The more vinegar that is used, the lower the pH of both the limewater and the aquarium will be. One reasonable point to shoot for is to add about the same amount of total CO2 via the vinegar as is needed by the lime to form HCO3-. This balance is roughly matched by using three level teaspoons of solid lime per gallon of limewater, and 45 ml of vinegar per gallon of limewater. For those aquarists choosing to use vinegar in limewater, these values are a suitable starting point. Note that the pH of the limewater is still quite high, so slow dosing is usually required.

What kind of vinegar should be used? Luckily, cheap distilled white vinegar is likely the best. More expensive flavored and colored vinegars, such as red wine vinegar, will deliver other unnecessary organic molecules to the aquarium, and are best avoided.

[HighlandReefer]

The vinegar has a temporary pH reducing effect as the bacteria add the OH- back quickly. I have not seen any significant lowering of pH while using vinegar. Randy has made the same statement & he uses a lot of vinegar. There are limits to the amount of vinegar you can safely dose. ;)

[Wildman]

Excellent! Thanks.

[HighlandReefer]

Your welcome. ;)