Matt, The 18 gallon has the same print as a 10 gallon, just taller. Yes, it is a lot of light for such a small tank, but as the tank is so deep I decided to go with the 250. This topic has been discussed on Reef central and Nano Reef a lot and with proper ventalation, everything should be okay. The lamp will be almost 11 inches off of the water as well. There is even guys out there with incredible 7 gallon mini bows with 175's on em! It's crazy, but they are beautiful. Also, if I buy the 250 and I want a larger tank one day, I can always transfer it.

Thanks again
~Dust