new to saltwater - need some advices

Hi, my name is Dan.



I have a 90g freshwater tank. Now I want to try saltwater. it will be mainly fish tank and little reef.



1. I have some really nice looking rocks from freshwater, can I use them for saltwater?

2. What size is good sump for 90g tank?

3. What type of skimmer is good for 90g tank?





Thank you.