Personally I never had RTN result from too much light. Usually just a quick bleaching of the coral. Yes you have a lot of light, but RTN from that I do not see. Do you see PE with either new coral? They could have been traumatized during shipping with big temp swings and the result is tissue loss. As long as you see some PE either at night or during the day I would not change the flow yet. My Valida shows the best PE at night. If they loose color move them down some and perhaps consider a different dip. Please let us know how it goes.