My daily juice is a light gold colored Marlboro flavor. About 3 days on a clearo and I can see the light gold color start to darken at the bottom of the tank, because I never let it get to rock bottom before refilling it. So, after 3 or four days I break it down, run the atomizer/wicks under hot but slow running water, working the wicks clean with my fingers and lightly blowing water through the atomizer itself. I dry it lightly with a paper towel, lightly blow out any remaining water, dry out the tube, dry everything off gently and put it back together. I then refill it, giving it the standard couple of minutes for the wicks to get juice up into the head, then I start vaping away.
No down time and so far no problems with my method. They perform and taste like new.