For the first time ever after removing pumps and consolidating them into one large pump to a manifold I just realized that I'm going to seriously need a heater. Last night my temperature dropped to 73.9 according to the Apex and it hovers around 75 normally and 77.8 with the Metal Halides on. Err... Is this OK? My fish seem FINE and the coral seems ok though I don't have much. Mostly Ricordea's and a few SPS. What kind and how many heaters you folks think I'll need for my tank? I got a 150 with 40 gal breeder Sump.