Start with clean tubes with no solids or precipitate caking the insides already. If you don't have fresh tubing to run the lines then flush them with RODI or distilled water til they clear out completely. Then use only a clear, non-crystallized KH component for dosing. Make sure the tip of the dosing input line does not touch the water level in the tank or sump even with the power off. You should never have buildup in your tubes in this scenario. It's typically cause by a kh component that is on the brink of solidifying due to low temps or very high concentration. Some come with precipitate already in the bottom of the container so you need to be sure to full reheat and dissolve any Kh component so it's perfectly clear and liquid before use. Best of luck!
