Thanks for the tip Murphy.
When I had my Discus tank, I use to work at a Pet Store and worked on the day that we received fresh shipments of tubifex and blackworms, so I was able to get them pretty fresh.
I had my Discus tank up and running for over year and looking great when it crashed on me all of a sudden. I lost a lot of my tetras and a pair of my super reds. I always wonder if the there was a build of worms within the tank that contaminated it and spread a disease. I did regular water changes and constantly checked my water chemistry, but was not sure.