I bought a Big Baby tank and it has an RBA with it. I threaded some cotton through the coils that are provided and, on my second attempt I've got it to work really well. My question is how long will the coils typically last before I need to replace them. I know I can pull out the old cotton and dry fire the coils to burn off the crap then re thread them. How often can I do this before I need to replace the wire? I'm a newbie at rebuilding coils.