Re: sorry to ask but...
I use canned compressed air, to clean my hoses. The same that I use to blow dust off my computer. Just hold the nozzle to the hose opening, and presto. Then blow it out, normally, to make sure you have all of the propellant out.
Sounds like your cafe, is using a low-brand shisha, and also that the coals may be too hot, and the flavor is burning up. Try using just enough coals, to get moderate smoke.