As you can see not all tubing is created equal. Companies that use tubing layered with films called (MPF) or multi polymeric films can degrade over time when exposed to even minor uv rays. This degradation causes the tubing to turn a golden brown and or delaminate.  When this happens  the lighting will change inside your home. That once beautiful white light you experienced when your tube was new can now be an ugly yellowish brown. So how can this be resolved? Do all tubes us this multi polymeric film? NO! Using tubing such as Spectralume, manufactured by a german company called Alanod which uses a special process to chemically bond this mirror like coating to the aluminum substrate. This will never delaminate because simply, it isnt a film but a coating. It will not degrade becuse it is uv stable. So your tubing will stay crystal clear now and years to come.