I've experienced the exact same thing lately. We ran out of the stock tubing on our Omax, and all I could find in the mean time was some nylon. Every 5-10 minutes I kept hearing a large *crack* and then I finally saw a huge spark come off of the tubing. Anyway - the stock tubing is from Saint Gobain called Tygon I can't remember the exact model #, but I'll try to take a look tomorrow. You should get rid of the nylon and you wont have any more issues.