Tank Conversion Help!

[Glanier]

So my stepdad just gave me his old 75 gallon saltwater tank with a bioball system and all. My question is, how do i clean the bioball/filter system under the tank? I've seen 3 different website say use vinegar and water to clean out the inside of the actual tank and use a diluted bleach solution to clean off the rocks he had in it so I can use those, but I have not seen anything on how to clean the bioball/filter system. Can anyone please tell me what to do? P.S I have 2 Oscar Cichlids!
Thanks in advance!!

 

[Glanier]

Here is the tank and system up under it