I didn't need to during my fallow period. I just kept feeding my corals and occasionally threw in an algae wafer and a shrimp wafer from my freshwater food supplies. The wafers helped to keep the crabs and shrimp from stealing food from the corals. The residual waste should be enough to keep your bio filter running. Just be careful not to overload with fish when you reintroduce them. If they all make it through quarantine then maybe add half of them back for a week before adding the other half.