just a heads up... I had a 25 with a 150 sunpod and experienced massive evaporation and had a hard time keeping the temp and chemistry constant. Quite honestly I had to do top offs every day and 5 gallon water changes 3 times a week. Being a full time student and working, I got got kinda burnt out with it and switched to a 60 gallon fowlr. 250 watts gives you right around 10 wpg. From my understanding 7 will grow anything. Also, a lot of soft coral do not like very strong lighting if you plan on having both. A 150 would probebly be perfect, you could always get another from when you upgrade. If you go with the 250 I would reccommend hanging it about 2 feet above your tank to help with the evap and temp. Its not that hard to keep your reef great, but with small tanks, you have to be vigilant on a daily basis. If your a busy person and would be able to dedicate a portion of your time everyday, then your reef will stay amazing. I hope you can avoid some of the problems that I faced. Good luck
-Nick