Kalkwasser and Alkalinity Questions

Does Pickling Lime Kalkwasser raise both Calcium and Alkalinity at the same time?  I've heard both no and yes answers on the internet and various books.   Ether way, can a person use baking soda to raise ALK or is the Kent Reef Builder better? 


Edited by ajkochev - May 31 2010 at 5:33pm

From what I understand it does not really raise either if being done properly nut it keeps both in the range they need to be in.  SO if one or the other is off you would need to add something to raise or lower it than you would keep dosing kalkwasser to keep both at those levels.  Thats how I understand it at least.  If you overdose the kalkwasser it can overdose your tank on both but scariest of all is it will send your pH sky high.

I agree with most of what has been said. It's unfortunate that it is so difficult to find the truth among so many opinions found in books and the internet. Maybe together we can decipher the meaning of what is out there.

I don't know the details of the chemistry but I know what it does in a reef aquarium. Kalkwasser means "chalk water". It's a German term because that's where they first started using chalk/lime dissolved in water to add Ca to reef aquariums. What we later realized is that it adds both Calcium and Alkalinity, but there are a few problems with it's use:

1- Kalkwasser solution has such a high pH (~30) that it cannot be added in large quantities. I believe that a pH of 30 is ~3000 times higher than 8, so it will burn anything it touches. Aquaristnewbie appropriately warned us of that.
2- Kalkwasser may not be able to keep up with the Alk and Ca needs of a tank, especially these days with so many people keeping so much stony coral, growing Coralline algae and keeping enough snails to prevent algae problems.
3- Kalkwasser powder (technically known as Calcium Hydroxide) should never be placed directly in the tank. Rather it should be used in diluted form in top-off water as Badfinger so effectively pointed out.

Now for the question about Baking Soda vs. Kent Reef Builder.
Either one can be used interchangeably. Baking Soda is Sodium Bicarbonate (NaHCO3). It is one of two ingredients in Kent Reef Builder. The other ingredient is Soda Ash also known as Washing Soda and Sodium Carbonate(Na2CO3). The reason for the soda ash is to eliminate a single relatively insignificant effect of a temporary increase in pH when Baking Soda is used alone.

Anyone can make their own "Reef Builder". It's done by taking a small box(1 lb.) of Baking Soda and spreading it out in a glass baking dish. it is baked in the oven at 400 degrees for 1 hour. After it cools, thoroughly mix it with four boxes of Baking Soda. So for about $1/lb. you can make 5 lbs. of the same stuff that sells for about $9/lb. on the internet.  $5 vs. $45+

The use of any additive/chemical to a reef aquarium should always be preceded by testing and only when testing indicates the need, should anything be added.


Edited by Mark Peterson - June 01 2010 at 6:17pm

I said that baking soda alone increases pH temporarily, but Jerry is right it's a temporary decrease.

I don't even measure it anymore.
It's about 1+ tablespoon per cup of RO water
Mix in as much as will dissolve and leave the residue in there. When all the fluid is gone add more RO water to dissolve the residue and add some more powder.

I believe that is also in my old thread that I just today realized I ought to have linked in my signature. Doh!

Lewy wrote: Thanks Mark.  You almost need your own section for reference.

+1