try the two 150s, but it depends on the total water volumn and room temp...I have to use three 200s on my 90 because it's plumbed down into the basement.
I ran two 150s on my 120. For $99 you could get a Reef keeper light that will control the temp +. I'm considering getting one myself as right now I'm relying on the heaters themselves ;(
i have a neptune JR. monitoring my 120G. I currently have a 150 and 100 Watt heaters in the sump. Just wondering if i should use (1) 250 or 300watt. the tank is located downstairs of my house, at the thermistat is set at 66 at night.