used chiller cleaning

[pirate]

Well I got a used chiller the other day that has not been used for about 4 months now, and they left the water in it . I know it was not used for a reef befor I got it, it was used for a green house. What is the best way to clean it now? I'm thinking about running clean water thru it till its clean and then used salt water from the tank. Is there something else that I can do or use?