Hi, In the past I sucessfully kept up to 3 freshwater tanks at a time. I have been out of the hobby for about 5 years. Recently My daughter gave me her whole saltwater set-up. I want to set up a freshwater tank. I have thoroughly cleaned all equipment with vinegar and rinsed well. Is there anything else I should be doing to convert to a freshwater tank. I would also like to use her rock. Is this okay or might there be too much residue left in it that will be harmful?