I have been quite busy lately and have not had the time to resolve my over flow noise yet.
Only thing I have in my sump is my skimmer. Because I am cycling and other important things in life, I will leave the skimmer off for now until at least im further into the cycle. Which allows me to run my tank without the overflow for now.
Yes it is coral life 2x 150. Do you already have these lights setup? If so, just put your hand under that for a few min. It almost starts to somewhat burn your hand mildly. I dont see how that can not heat up the water.
Moreover, the instruction manual said not to use these lights in a open hood environment. So I put a glass top on the tank. Which creates a microwave effect, (kinda like parking a car in the sun in summer) which heats up the tank more I can imagine.