10 Gallon

Hello, I'm new to this forum, I hope I'm posting in the right section. I've owned a 10 gallon Glofish freshwater tank for 6 months with great results, but I'd really like to change it into a saltwater tank. I would like to keep two clownfish. I know that I'll need to replace the gravel with sand, and I know that I'll need some live rock and a coral, and I'll need to purchase some new conditioner for the saltwater. Is there anything else I'll need? I have a filter and a tropical fish water heater, will I need both of those? Will I need a saltwater specific filter?