If you filters are large enough and well cycled they should always keep ammonia and nitrites at 0. Its only the Nitrates that go up. There are also auto feeders, I am not too sure on the cost cause I never have a real need (yet) for something like that. But I suppose it is filled with flakes and/or pellets and a timer drops them as you program it to. I would use it for a while before letting it go on its own. I read one guys disaster story here how the feeder dumped everything the first day.
