To give you an idea what 10kw can power. You can power you home A/C unit, a refrigerator, lights, and a TV at the same time.
For just the system, especially if you are using all DC pumps. I agree and suggest a small Honda generator, that will run your reef tank.
I bought a propane generator from
Central Main Diesel. Burns cleaner, and no problems with storage and fuel going south.
Note:
If you by a gasoline engine generator, run ethanol free gasoline. Ethanol is really bad for small engines. It eats away at the rubber hoses, internal seals, and gum up the carburetor. Most of the time when your mower will not start, it is the ethanol in the gas that's messing up the carburetor.