I clean my main ones at the end of the week, or every few days depending on usage. Use an o-ring pick to pry out the o-rings, toss them in some boiling water, and leave them for an hour or two.
If you want to avoid boiling water, you can mix some lemon, baking soda, and water. A local Hookah lounge used to do this to clean their hoses. You will get a lemon taste after the first drag but that should fade away quickly.