Well it depends most leather corals need brighter light to grow fast but need moderate flow. So my question is what leather coral are u talking about. For ur high, medium, low all its saying is what kind of light it needs to survive. Ur mh or T5 are ur brighter lights, power compacts are ur more medium lights and ur just florecent bulbs are u lower lights. What kind of lights do u have, remember if u have power compacts u can move ur coral higher on the rocks to get more light.