I am interested in buying a kayfun because there's so much talk about how good it is, however when I looked it up and checked it out I noticed that the the tank is made of plastic. Is this an issue? Does it crack very easily from some liquids? I wouldn't want to buy it to accidentally crack it an hour later. I have a liquid I really like but it is a "tank cracker". I know that some of them also come with metal but I like to see how much liquid I've got left. Are there any other good alternatives?