20 Chapter 1 Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery. 39Copyright (c) 2005 John Wiley & Sons, Inc.Chapter 1 Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery. 40Copyright (c) 2005 John Wiley & Sons, Inc.
Water hardness is a measure of the dissolved mineral content of water. There are two types: the general hardness (GH) and carbonate hardness (KH). When keeping freshwater fish and plants, the GH and the KH of aquarium water should match their natural habitat.
The two most common instruments used to measure DBH are a girthing (or diameter) tape and calipers. A girthing tape actually measures the girth (circumference) of the tree; the girthing tape is calibrated in divisions of Ï centimetres (3.14159 cm).