I do beleive that is what tis is called my rocks and substrate are all covered up in brown colored stuff(diatoms). I am currently running a 55gallon tank with a 300g overflow 600 gal return pump. Fish is also stocked with a 6 line wrasse' 2 fancy clowns' 1 fire fish' 1 purple fire fish, and 2 peppermint shrimps. What is the correct reef cleaner pack that should be added to control this? Should I be worried about the live stock that are currently living in my tank?