Your trichlor is probably still okay to use, if you've opened the container and found dry pucks. You may have lost a little of the chlorine strength, but that's okay--and the safest way to dispose of them is in your pool, anyway. However, the trichlor will drive your pH down anyway, so I wouldn't use them until you know you have the pH under control. If you've lost more than 1 ppm chlorine overnight, then you need to shock the pool up to 15 ppm and try to hold it there until you're NOT losing any chlorine at night. Then you can let it come down and start adding CYA.

Janet