There are several things to consider when selecting a hose to convey powder from the powder pump to the spray gun. For manual spray guns, hose flexibility is important. If you will be spraying different types of powders or different colors through the same hose, it needs to be easy to clean. Abrasive materials will require the use of a very durable hose. Most powder hoses range in size from 0.375" inside diameter (ID) to 0.75" ID. Typically, 11 mm or 7/16" ID hose is used. If your application requires high powder flow, you may need a hose with a larger ID. For applications of low powder output, a smaller ID hose will give better control of the powder delivery. Many different types of powder hoses are now available, and each one is designed for a specific purpose. For your application, I would suggest a conductive powder hose. Because you make frequent color changes, using this hose will help to speed up color change a great deal. The conductive nature of the hose resists impact fusion and is easy to clean so you should not have to use cleaning cubes or a hose-cleaning gun.