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.
PSI: Pounds per square inch measures the pressure, or cleaning force, of water created through the pressure washer. Use the PSI rating to help you determine how powerful the water stream will be. GPM: Gallons per minute measures the volume of water delivered through the pressure washer.