otem
Most people recommend a quality protein skimmer(Euro-Reef, Aqua C,etc..) While some can succeed witout one, they are usually extremely lightly stocked with fish, and/or have HUGE refugiums, and/or do very frequent water changes, etc... Nutirents must be exported somehow.
Witout knowing your inhabitants, etc... I would personally remove the bio-balls (slowly) and get a qulaity skimmer.
BTW an excellent book is The Conscientious Marine Aquarist: A Commonsense Handbook for Successful Saltwater Hobbyists
by Robert M. Fenner,
HTH