Hrmz, agree with the bros that the temperature is definately not the caused of the deaths. In any case, the shrimps which is much more sensitive to high temperature would proberbly perish way before your clowns if its due to high temperature. Did you ensure your ammonia, nitrite and nitrates were in acceptable levels after you changed your LRs? If possible try get a HOB filter with surface skimming capability. It'll help filter away the top layer of "oil". Whats the flowrate of your filter?