Guess the big question is what sort of fish are you stocking it with. If you have cichlids, they stir the gravel constantly with there digging. All large tanks I know have there wc done with a garden hose. Put one end in, turn tap on enough that water has a flow happening then pop it off the tap and it starts siphoning out itself. Undergravel filters are useless IMO. My biggest concern is that it will block up.
I never worry about the gravel too much, if I get a bit if build up, next time cleaning, I stir the gravel with my fingers while holding the siphon hose.