I have a soft tub. Can I use the trouble brand shock in this type of tub?

As long as you brush it around until is is fully dissolved. They make special shock for vinyl liner pools, but you should still think of brushing it. As an alternative, you can add the shock to a bucket of water and stir it until it dissolves and then pour it in the pool. **** SPECIAL NOTE **** ALWAYS, ALWAYS, ALWAYS add any chemical to water, NEVER add water to the chemical.

Might want to check into using liquid shock, although it raises pH slightly, a lot easier to use.