Is it recommended to not use dark juices in a tank system at all? Or do you just have to clean it more? I've just received some 30ml juices from a vendor and one of the flavors is very dark and I've heard it can gum up tank systems. I haven't cleaned my atty at all yet but I think I will try the soak in boiled water method first when I do. It seems the easiest to do. Unless someone has a simple alternative.