No talk yet on a chiller for a 700 gal tank. You will need at least a 1 hp unit. This will require a 20amp 220 volt. And professional installation. And yes, large tanks take more maintenance, figure 2-3 times what you spend on your 100 gallon. Cost factors can range from 75.00 to 100.00, that's per gallon for a full stocked reef. I know some people will say that's overpriced. I myself think that's about average. One thing is if you try to cut corners in the beginning. You and your livestock will only suffer down the road. As far as power goes I spend about 350.00 to 400.00 on the tank alone per month. And don't forget about back up's for everything. Just to be safe. I have a back up chiller on it's own circuit. Back up pumps, I run 9 on my system. Also have back up ballast's. With a larger tank, you can't just go to the local fish store when something breaks.... Better to be safe than sorry...
Good Luck, this is a great hobby.
Good Luck, this is a great hobby.