We use IV Prep wipe under the site and it sticks very well for us. I did buy this http://my.medtronicdiabetes.com/ec_ProductDetail?pid=a1SC0000000LqzCMAS in case we do stomach sites. Those don't stay on for us well. These work on Animas or Minimed sets. I use to have bubbles in the tubing more often in the years past on the Cozmo. I just don't know why. I still use the same method of taping with a pen. I do keep the insulin (even opened) in the fridge now. Thought I had heard that that would cause bubbles, but is the opposite for us. I think you can have a bad site but not totally bad. If we have ketones on the blood ketone meter then I always change the site out. Or if several corrections do not seem to be working. Seeing a bubble in the bottom of cartridge doesn't always mean you had one come out.