I opened my pool recently and purchased some new shock at Home Depot the main ingredient is Trichloro-s-triazinetrione a powder. I had some shock left over from last year which main ingredient is sodium hypochorlite a liquid shock. The Trichloro on the top said do not mix with calcium hypochorite why not and what is that another type of shock? What is the difference between sodium hypochorlite and calcium hypochorite. I never mixed the two I just used the Home Depot one. My other question in the future would it okay to use the liquid shock from last season. Thanks!