I've had mine for maybe 3 months..I'm still using the same sera filler that I started with, I just take it out and rinse it off every once in a while. I traded my zap for it and the guy sent along a sheet of sera. I've read that cotton would work as a filler but I haven't tried it.
It's an interesting atty. I only use a diy peach juice in it and get thick, rich clouds. When I fill it, I don't get near the vape time as I do with say, the KFL before it starts needing juice again. It's kinda like a big cartomizer but the filler doesn't heat up and get gummy. It's not messy to refill. It takes a bit of trial and error to gauge how much filler to use and how long the wicks need to be. I'm sure you'll figure it out in no time. I look forward to hearing your thought on it once you get it.