Hello! I have done some research and I’m ready to start my first saltwater tank. I found a very cheap 32.5 Gallon Fluval Flex used for saltwater up for sale (used) and I’m thinking of buying it. With a few adjustments in lighting and powerheads, I want to turn it into a reef tank. The tank itself has a built in filter in it, but I need help on deciding what filtering material I would need. Any suggestions?