Make a Clean Tube Cut
Bulkreefsupply.com recommends using a tube cutter for a nice clean cut. Cut the tube squarely and ensure that the cut has not made the tube out of round and that the tube has a smooth outside diameter without any burrs or score marks prior to inserting it into the fitting.
Insert Tube into Fitting
Push the tubing through the collet and dual o-rings until it "bottoms out" against the tube stop.
Test and Inspect
Push and pull the tubing toward and away from the fitting to ensure that is has been installed properly. Test and inspect the installation for any leaks.
Relieve pressure from the tubing and fitting. Push uniformly around the collect flange against the fitting body while pulling the tubing away from the fitting to release it.