Background 65 gallon tank 2.5 inch sand bed, 20 lbs of crushed coral/fine sand layer on top. temp 77.0, salt 1.025, ph 8.2, amm 0, nitrites 0, nitrates 10-20 tank is 6 weeks old. fish and corals are all healthy now. Questions I need answers to: 1. When feeding DT plankton and other quickly water soluable substances is it good to shut downt he overflow & return leaving only the powerheads running in the tank? 2. If so, for how long should they be off? 1 hour? more?