What's the difference b/t KH and dKH?

[brianjfinn]

What's the difference between Carbonate Hardness (KH) and Alkalinity (dKH)?

 

[ichthyoid]

brianjfinn;450054 wrote: What's the difference between Carbonate Hardness (KH) and Alkalinity (dKH)?

Here's what Randy Holmes-Farley says on the matter:

<p style="text-align:left"><span style="font-family: Times New Roman">Finally there is the German term dKH (degrees of carbonate hardness), or just KH (carbonate hardness).Strictly speaking, it is the same as the carbonate alkalinity (AC in equation 8). Unfortunately, it is a very confusing term, as it has nothing to do with hardness. Further, it has been corrupted by the marine aquarium hobby to mean the same as total alkalinity, and every test kit that tests for dKH with a single titration is giving total alkalinity. The only kit that I am aware of that even makes a distinction between carbonate alkalinity and total alkalinity is one of the <span style="color: #000000">http://www.seachem.com/en_products/product_pages/0924_RS_mgnsm.html"><u>Seachem kits</u></a></span> (Reef Status: Magnesium, Carbonate, & Borate) and it thankfully doesn’t use the term dKH at all. Consequently, most hobbyists should think of dKH as simply another measure of total alkalinity. The results obtained with such a kit (dKH) can be divided by 2.8 to yield the alkalinity in meq/L. </span>

Complete article, if interested:

[IMG]http://www.advancedaquarist.com/issues/feb2002/chemistry.htm">http://www.advancedaquarist.com/issues/feb2002/chemistry.htm</a>

 

[ryuchi]

BTW I just bought that seachem kit and it is very sensitive and takes about 30 minutes to do both tests (total dKH and alk from borate, you then subtract the borate alk from the total alk to get your real KH. It can be frustrating if you are off half a drop on the borate test the results can be off by about 30%, however I feel very confident about the accuracy of the test compared to others.

 

[brianjfinn]

Thanks guys! Ichthyoid, I always look forward to your responses!

 

[ichthyoid]

You are quite welcome, my friend!