When I first started I noticed people talking about having multiple tanks. When I used PT2s, they were simple to clean, but I let them air-dry, so I had a few tanks. I change flavors (tanks) throughout the day because my taste buds get overwhelmed and I lose the flavor for that juice. I generally have 4-6 tanks running at once. I like a pastry with my morning coffee and in the evening in front of the TV, I need less nic because I am vaping more. That is two right there.
Anyway, I disassemble the tank/coil and toss it all into water/vinegar bowl for an hour and then rinse under the hottest tap water. Even the bowl of vinegar/water lasted a while.
Juice does change color a bit, but never black. About 10mg and wash.
Pretty easy.